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ContentsContents
AppStream
  1. 1 About AppStream
  2. 2 Upstream Metadata
  3. 3 Catalog Metadata
  4. 4 Miscellaneous
  5. 5 Metadata Quickstart
  6. 6 Data Validation
  7. 7 Manual pages
      appstreamcli 2012-2024Matthias Klumpp AppStream 26 July,2012 appstreamcli1appstreamcliHandle AppStream metadata formats and query AppStream dataappstreamcliCOMMANDDescription This manual page documents briefly the appstreamcli command. appstreamcli is a small helper tool to work with AppStream metadata and access the AppStream component index from the command-line. The AppStream component index contains a list of all available software components for your distribution, matched to their package names. It is generated using AppStream XML or Debian DEP-11 data, which is provided by your distributor. For more information about the AppStream project and the other components which are part of it, take a look at the AppStream pages at Freedesktop.org. Optionsget IDGet a component from the metadata pool by its identifier.ssearch TERMSearch the AppStream component pool for a given search term.what-provides TYPE TERM Return components which provide a given item. An item type can be specified using the TYPE parameter, a value to search for has to be supplied using the TERM parameter. Examples: Get components which handle the "text/xml" mediatype. appstreamcli what-provides mediatype "text/xml" Get component which provides the "libfoo.so.2" library. appstreamcli what-provides lib libfoo.so.2 refreshrefresh-cache Trigger a database refresh, if necessary. In case you want to force the database to be rebuilt, supply the --force flag. This command must be executed with root permission.status Display various information about the installed metadata and the metadata cache. os-info Show information about the current operating system from the metadata index. This requires the operating system to provide a operating-system component for itself. dump ID Dump the complete XML descriptions of components with the given ID that were found in the metadata pool. validate FILES Validate AppStream XML metadata for compliance with the specification. Both XML metadata types, upstream and distro XML, are handled. The format type which should be validated is determined automatically. The --pedantic flag triggers a more pedantic validation of the file, including minor and style issues in the report. validate-tree DIRECTORY Validate AppStream XML metadata found in a file-tree. This performs a standard validation of all found metadata, but also checks for additional errors, like the presence of .desktop files and validity of other additional metadata. check-license LICENSE Test a license string or license expression for validity and display details about it. This will check whether the license string is considered to be valid for AppStream, and return a non-zero exit code if it is not. The command will also display useful information like the canonical ID of a license, whether it is suitable as license for AppStream metadata, and whether the license is considered to be for Free and Open Source software or proprietary software. AppStream will consider any license as Free and Open Source that is marked as suitable by either the Free Software Foundation (FSF), Open Source Initiative (OSI) or explicit license list of the Debian Free Software Guidelines (DFSG). install ID Install a software component by its ID using the package manager or Flatpak. This resolves the AppStream component ID to an installation candidate and then calls either the native package manager or Flatpak (if available) to install the component. remove ID Uninstall a software component by its ID using the package manager or Flatpak. This will uninstall software matching the selected ID using either the native package manager or Flatpak (if available). put FILE Install a metadata file into the right directory on the current machine. compare-versionsvercmp VER1 [CMP] VER2 Compare two version numbers. If two version numbers are given as parameters, the versions will be compared and the comparison result will be printed to stdout. If a version number, a comparison operator and another version number are passed in as parameter, the result of the comparison operation will be printed to stdout, and appstreamcli will exit with a non-zero exit status in case the comparison failed. The comparison operator can be one of the following: eq - Equal tone - Not equal tolt - Less thangt - Greater thanle - Less than or equal toge - Greater than or equal tonew-template TYPE FILE Create a metainfo file template to be used by software projects. The --from-desktop option can be used to use a .desktop file as template for generating the example file. The generated files contain example entries which need to be filed in with the actual desired values by the project author. The first TYPE parameter is the name of an AppStream component type. For a complete list check out the documentation or the help output of appstreamcli for this subcommand. make-desktop-file MI_FILE DESKTOP_FILE Create a XDG desktop-entry file from a metainfo file. If the desktop-entry file specified in DESKTOP_FILE already exists, it will get extended with the new information extracted from the metainfo file. Otherwise a new file will be created. This command will use the first binary mentioned in a provides tag of the component for the Exec= field of the new desktop-entry file. If this is not the desired behavior, the --exec flag can be used to explicitly define a binary to launch. Other methods of launching the application are currently not supported. In order to generate a proper desktop-entry, this command assumes that not only the minimally required tags for an AppStream component are set, but also that it has an <icon/> tag of type "stock" to describe the stock icon that should be used as well as a <categories/> tag containing the categories the application should be placed in. news-to-metainfo NEWS_FILE MI_FILE [OUT_FILE] This command converts a NEWS file as used by many open source projects into the XML used by AppStream. Since NEWS files are free text, a lot of heuristics will be applied to get reasonable results. The converter can also read a YAML version of the AppStream release description and convert it to XML as well. If the metainfo file MI_FILE already exists, it will be augmented with the new release entries, otherwise the release entries will be written without any wrapping component. If [OUT_FILE] is specified, instead of acting on MI_FILE the changed data will be written to the particular file. If any of the output filenames is set to "-", the output will instead be written to stdout. The --format option can be used to enforce reading the input file in a specific format ("text" or "yaml") in case the format autodetection fails. The --limit option is used to limit the amount of release entries written (the newest entries will always be first). metainfo-to-news MI_FILE NEWS_FILE This command reverses the news-to-metainfo command and writes a NEWS file as text or YAML using the XML contained in a metainfo file. If NEWS_FILE is set to "-", the resulting data will be written to stdout instead of to a file. The --format option can be used to explicitly specify the output format ("yaml" or "text"). If it is not set, appstreamcli will guess which format is most suitable. convert FILE1 FILE1 Converts AppStream XML metadata into its YAML representation and vice versa. compose Composes an AppStream metadata catalog from a directory tree with metainfo files. This command is only available if the org.freedesktop.appstream.compose component is installed. See appstreamcli-compose1 for more information. --detailsPrint out more information about a found component.--no-colorDon't print colored output.--no-netDo not access the network when validating metadata. The same effect can be achieved by setting the AS_VALIDATE_NONET environment variable before running appstreamcli. --versionDisplay the version number of appstreamcliSee Alsopkcon1.AUTHOR This manual page was written by Matthias Klumpp matthias@tenstral.net. appstreamcli compose 2020-2024Matthias Klumpp AppStream 28 Aug,2020 appstreamcli compose1appstreamcli-composeCompose AppStream metadata catalog from directory treesappstreamcli composeCOMMANDDescription This manual page documents briefly the appstreamcli compose command. The appstreamcli compose tool is used to construct AppStream metadata catalogs from directory trees. The tool will also perform many related metadata generation actions, like resizing icons and screenshots and merging in data from referenced desktop-entry files as well as translation status information. Therefore, the tool provides a fast way to test how the final processed metadata for an application that is shipped to users may look like. It also provides a way to easily generate AppStream data for projects which do not need a more complex data generator like appstream-generator. In order for the appstreamcli compose command to be available, you may need to install the optional compose module for appstreamcli first. For more information about the AppStream project and the other components which are part of it, take a look at the AppStream pages at Freedesktop.org. OptionsSOURCE-DIRECTORIES A list of directories to process needs to be provided as positional parameters. Data from all directories will be combined into one output namespace. --origin NAME Set the AppStream data origin identifier. This can be a value like "debian-unstable-main" or "flathub". --result-root DIR Sets the directory where all generated output that is deployed to a user's machine is exported to. If this parameter is not set and we only have one directory to process, we use that directory as default output path. If both --data-dir and --icons-dir are set, --result-root is not necessary and no data will be written to that directory. --data-dir DIR Override the directory where the generated AppStream metadata catalog will be written to. Data will be written directly to this directory, and no supdirectories will be created (unlike when using --result-root to set an output location). --icons-dir DIR Override the directory where the cached icons are exported to. --hints-dir DIR Set a directory where hints reported generated during metadata processing are saved to. If this parameter is not set, no HTML/YAML hint reports will be saved. --media-dir DIR If set, creates a directory with media content (icons, screenshots, ...) that can be served via a webserver. The metadata will be extended to include information about these remote media. --media-baseurl URL The URL under which the contents of a directory set via --media-dir will be served. This value must be set if a media directory is created. --prefix DIR Set the default prefix that is used in the processed directories. If none is set explicitly, /usr is assumed. --print-report MODE Print the issue hints report (that gets exported as HTML and YAML document when --hints-dir was set) to the console in text form. Various print modes are supported: on-error only prints a short report if the run failed (default), short generates an abridged report that is always printed and full results in a detailed report to be printed. --no-partial-urls If set, all URLs in the generated data will be absolute and media_baseurl will not be used. This makes changing the media mirror harder without regenerating all data and is generally not recommended, to increase flexibility. --icon-policy POLICY-STRING Override the existing icon policy with a custom one. The icon policy sets how icons of different sizes should be dealt with. They can be in the icon cache only, be a remote icon in the media location or be both cached and available in the remote location. The icon-policy string is comprised of comma-separated %{size}x%{size}@%{scale}=%{state} statements. The size and scale are that of the respective icon, with the scale being allowed to be omitted if it is 1. The state can be one of remote, cached or cached-remote. By default, a policy of 48x48=cached,48x48@2=cached,64x64=cached,64x64@2=cached,128x128=cached-remote,128x128@2=cached-remote is selected. --allow-custom CUSTOM-KEY-NAMES By default, all custom entries set in MetaInfo input data are removed. This flag allows to whitelist custom keys to be propagated to the final catalog output data. The custom-key names should be provided as a comma-separated list. --components COMPONENT-IDs Set a comma-separated list of AppStream component IDs that should be considered for the generated metadata. All components that exist in the input data but are not mentioned in this list will be ignored for the generated output. --no-colorDon't print colored output.--verboseDisplay extra debugging information--versionDisplay the version number of appstreamcli composeSee Also appstreamcli1, appstream-generator1. AUTHOR This manual page was written by Matthias Klumpp matthias@tenstral.net.
  8. 8 AppStream API Reference
  9. Index
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Applies to AppStream 1.0

6 Data Validation

These pages contain various information on AppStream metadata validation.

6.1 Validator Issues

6.1.1 Introduction

The AppStream utility appstreamcli validate can validate all kinds of AppSteeam XML metadata. It will emit a variety of hints with different priority:

Error hints render the data unusable or severely limit its usefulness and make it fail validation. Warnings warn about likely unintended behavior, typing errors or issues which might cause data to not be displayed or improperly read. They fail validation, but may be ignored in some circumstances. Info hints are optional recommendations to make the data better, while pedantic hints are nice-to-have. The latter are not displayed by default unless the tool is in pedantic mode.

This document contains a list of all issues checked for by appstreamcli validate.

6.1.2 Validator Issue Tags

This is a list of all possible validation issues that appstreamcli can detect.

type-property-required 

Severity: error

This tag requires a type property.

invalid-child-tag-name 

Severity: info

Tags of this name are not permitted in this section.

metainfo-localized-description-tag 

Severity: error

A <description/> tag must not be localized in metainfo files (upstream metadata). Localize the individual paragraphs instead.

catalog-localized-description-section 

Severity: error

This element (paragraph, list, etc.) of a <description/> tag must not be localized individually in catalog metadata. Localize the whole <description/> tag instead. The AppStream metadata catalog generator (e.g. `appstream-generator`) will already do the right thing when compiling the data.

description-markup-invalid 

Severity: error

AppStream descriptions support only a limited set of tags to format text: Paragraphs (<p/>) and lists (<ul/>, <ol/>). This description markup contains an invalid XML tag that would not be rendered correctly in applications supporting the metainfo specification.

description-para-markup-invalid 

Severity: error

This description paragraph contains invalid markup. Currently, only <em/> and <code/> are permitted.

description-enum-item-invalid 

Severity: error

Enumerations must only have list items (<li/>) as children.

description-enum-group-translated 

Severity: error

The enumeration must not be translated as a whole. In MetaInfo files, translate indivdual items (<li/> elements) instead.

description-first-para-too-short 

Severity: info

The first `description/p` paragraph of this component might be too short (< 80 characters). Please consider starting with a longer paragraph to improve how the description looks like in software centers and to provide more detailed information on this component immediately in the first paragraph.

description-first-word-not-capitalized 

Severity: info

The description line does not start with a capitalized word, project name or number.

description-has-plaintext-url 

Severity: warning

The description contains a web URL in plain text. This is not allowed, please use the <url/> tag instead to share links.

tag-not-translatable 

Severity: error

This tag is not translatable.

tag-duplicated 

Severity: error

This tag must only appear once in this context. Having multiple tags of this kind is not valid.

tag-empty 

Severity: warning

The mentioned tag is empty, which is highly likely not intended as it should have content.

tag-invalid-text-content 

Severity: error

The mentioned tag has text content, even though it must not contain text.

cid-is-not-rdns 

Severity: error

The component ID is required to follow a reverse domain-name scheme for its name. See the AppStream specification for details.

cid-desktopapp-is-not-rdns 

Severity: warning

The component ID is not a reverse domain-name. Please update the ID to avoid future issues and be compatible with all AppStream implementations. You may also consider to update the name of the accompanying .desktop file to follow the latest version of the Desktop-Entry specification and use a rDNS name for it as well. In any case, do not forget to mention the new desktop-entry in a <launchable/> tag for this component to keep the application launchable from software centers and the .desktop file data associated with the metainfo data.

cid-maybe-not-rdns 

Severity: info

The component ID might not follow the reverse domain-name schema (the TLD used by it is not known to the validator).

cid-invalid-character 

Severity: error

The component ID contains an invalid character. Only ASCII characters, dots and numbers are permitted.

cid-punctuation-prefix 

Severity: error

The component ID starts with punctuation. This is not allowed.

cid-rdns-contains-hyphen 

Severity: warning

The component ID contains a hyphen/minus in its domain part. Using a hyphen is strongly discouraged to improve interoperability with other tools such as D-Bus. A good option is to replace any hyphens with underscores (`_`). Hyphens are only allowed in the last segment of a component ID.

cid-has-number-prefix 

Severity: info

The component ID contains a segment starting with a number. Starting a segment of the reverse-DNS ID with a number is strongly discouraged, to keep interoperability with other tools such as D-Bus. Ideally, prefix these segments with an underscore.

cid-contains-uppercase-letter 

Severity: pedantic

The component ID should only contain lowercase characters.

cid-domain-not-lowercase 

Severity: error

The domain part of the rDNS component ID (first two parts) must only contain lowercase characters.

cid-missing-affiliation-freedesktop 

Severity: warning

The component is part of the Freedesktop project, but its ID does not start with fd.o's reverse-DNS name ("org.freedesktop").

cid-missing-affiliation-kde 

Severity: warning

The component is part of the KDE project, but its ID does not start with KDE's reverse-DNS name ("org.kde").

cid-missing-affiliation-gnome 

Severity: info

The component is part of the GNOME project, but its ID does not start with GNOME's reverse-DNS name ("org.gnome").

spdx-expression-invalid 

Severity: error

The SPDX license expression is invalid and could not be parsed.

spdx-license-unknown 

Severity: warning

The license ID was not found in the SPDX database. Please check that the license ID is written in an SPDX-conformant way and is a valid free software license.

metadata-license-too-complex 

Severity: error

The metadata itself seems to be licensed under a complex collection of licenses. Please license the data under a simple permissive license, like FSFAP, MIT or CC0-1.0 to allow distributors to include it in mixed data collections without the risk of license violations due to mutually incompatible licenses.

metadata-license-invalid 

Severity: error

The metadata itself does not seem to be licensed under a permissive license. Please license the data under a permissive license, like FSFAP, CC0-1.0 or 0BSD to allow distributors to include it in mixed data collections without the risk of license violations due to mutually incompatible licenses.

update-contact-no-mail 

Severity: warning

The update-contact does not appear to be a valid email address (escaping of `@` is only allowed as `_at_` or `_AT_`).

screenshot-invalid-env-style 

Severity: warning

The `environment` property is set to an unrecognized graphical environment/style combination.

screenshot-invalid-width 

Severity: warning

The `width` property must be a positive integer.

screenshot-invalid-height 

Severity: warning

The `height` property must be a positive integer.

screenshot-invalid-scale 

Severity: warning

The `scale` property must be a positive integer.

screenshot-image-invalid-type 

Severity: error

The image type must be either `source` or `thumbnail`.

screenshot-image-missing-width 

Severity: warning

The `width` property must be present if the image type is `thumbnail`.

screenshot-image-missing-height 

Severity: warning

The `height` property must be present if the image type is `thumbnail`.

screenshot-image-source-duplicated 

Severity: error

There can only be one `source` image per screenshot and language.

screenshot-image-no-source 

Severity: error

A screenshot must have at least one untranslated image of type `source`.

screenshot-image-no-source-but-en-locale 

Severity: error

A screenshot must have at least one untranslated image of type `source`, which could not be found. Instead, a tag with an `en` locale (`xml:lang=en`) was found, which is likely intended to be the translatable image. Please remove the XML localization attribute in this case.

screenshot-image-not-found 

Severity: warning

Unable to reach the screenshot image on its remote location - does the image exist?

screenshot-video-not-found 

Severity: warning

Unable to reach the screenshot video on its remote location - does the video file exist?

screenshot-media-url-not-secure 

Severity: info

Consider using a secure (HTTPS) URL to reference this screenshot image or video.

screenshot-no-unscaled-image 

Severity: warning

A screenshot must have at least one image that has a scaling factor of 1.

screenshot-no-media 

Severity: error

A screenshot must contain at least one image or video in order to be useful. Please add an <image/> to it.

screenshot-mixed-images-videos 

Severity: error

A screenshot must contain either images or videos, but not both at the same time. Please use this screenshot exclusively for either static images or for videos.

screenshot-no-caption 

Severity: pedantic

The screenshot does not have a caption text. Consider adding one.

screenshot-video-codec-missing 

Severity: info

The screenshot video does not specify which video codec was used in a `codec` property.

screenshot-video-container-missing 

Severity: pedantic

The screenshot video does not specify which container format was used in a `container` property.

screenshot-video-codec-invalid 

Severity: warning

The selected video codec is not supported by AppStream and software centers may not be able to play the video. Only the AV1 and VP9 codecs are currently supported, using `av1` and `vp9` as values for the `codec` property.

screenshot-video-container-invalid 

Severity: warning

The selected video container format is not supported by AppStream and software centers may not be able to play the video. Only the WebM and Matroska video containers are currently supported, using `webm` and `mkv` as values for the `container` property.

screenshot-video-file-wrong-container 

Severity: warning

For videos, only the WebM and Matroska (.mkv) container formats are currently supported. The file extension of the referenced video does not belong to either of these formats.

screenshot-default-contains-video 

Severity: error

The default screenshot of a software component must not be a video. Use a static image as default screenshot and set the video as a secondary screenshot.

screenshot-default-missing 

Severity: warning

No screenshot is marked as default.

relation-invalid-tag 

Severity: warning

Found an unknown tag in a requires/recommends group. This is likely an error, because a component relation of this type is unknown.

relation-item-no-value 

Severity: error

A `requires` or `recommends` item requires a value to denote a valid relation.

relation-item-has-version 

Severity: warning

Found `version` property on required/recommended item of a type that should not have or require a version.

relation-item-missing-compare 

Severity: info

Found `version` property on this required/recommended item, but not `compare` property. It is recommended to explicitly define a comparison operation.

relation-item-invalid-vercmp 

Severity: error

Invalid comparison operation on relation item. Only one of `eq/ne/lt/gt/le/ge` is permitted.

relation-item-has-vercmp 

Severity: info

The relation item has a comparison operation set, but does not support any comparisons.

relation-item-redefined 

Severity: warning

This relation item has already been defined once for this or a different relation type. Please do not redefine relations.

relation-memory-in-requires 

Severity: info

Found a memory size relation in a `requires` tag. This means users will not be able to even install the component without having enough RAM. This is usually not intended and you want to use `memory` in the `recommends` tag instead.

relation-control-in-requires 

Severity: info

Found a user input control relation in a `requires` tag. This means users will not be able to even install the component without having the defined input control available on the system. This is usually not intended and you want to use `control` in the `recommends` tag instead.

relation-control-value-invalid 

Severity: warning

This `control` item defines an unknown input method and is invalid. Check the specification for a list of permitted values.

relation-display-length-value-invalid 

Severity: warning

This `display_length` item contains an invalid display length. Its value must be a positive integer value denoting logical pixels. Please refer to the AppStream specification for more information on this tag.

relation-display-length-side-property-invalid 

Severity: warning

This `side` property of this `display_length` item contains an invalid value. It must either be `shortest` or `longest`, or unset to imply `shortest` to make the item value refer to either the shortest or longest side of the display.

relation-hardware-value-invalid 

Severity: warning

This `hardware` item contains an invalid value. It should be a Computer Hardware ID (CHID) UUID without braces.

relation-memory-value-invalid 

Severity: warning

A `memory` item must only contain a non-zero integer value, depicting a system memory size in mebibyte (MiB)

relation-internet-value-invalid 

Severity: warning

The set tag value is not valid for an `internet` relation.

relation-internet-bandwidth-offline 

Severity: warning

The `bandwidth_mbitps` property is not allowed when using `offline-only` as value.

relation-internet-bandwidth-value-invalid 

Severity: warning

The value of this property must be a positive integer value, describing the minimum required bandwidth in mbit/s.

component-type-invalid 

Severity: error

The set component type is not a recognized, valid AppStream component type.

component-priority-in-metainfo 

Severity: warning

The component has a priority value set. This is not allowed in metainfo files.

component-merge-in-metainfo 

Severity: warning

The component has a `merge` method defined. This is not allowed in metainfo files.

component-id-missing 

Severity: error

The component is missing an ID (<id/> tag).

component-name-missing 

Severity: error

The component is missing a name (<name/> tag).

component-name-too-long 

Severity: warning

The name of this component is excessively long and can likely not be displayed properly in most layouts.

component-summary-missing 

Severity: error

The component is missing a summary (<summary/> tag).

id-tag-has-type 

Severity: info

The <id/> tag still contains a `type` property, probably from an old conversion to the recent metainfo format.

multiple-pkgname 

Severity: pedantic

The `pkgname` tag appears multiple times. You should evaluate creating a metapackage containing the metainfo and .desktop files in order to avoid defining multiple package names per component.

name-has-dot-suffix 

Severity: pedantic

The component name should (likely) not end with a dot (`.`).

summary-has-dot-suffix 

Severity: info

The component summary should not end with a dot (`.`).

summary-has-tabs-or-linebreaks 

Severity: error

The component summary must not contain tabs or linebreaks.

summary-has-url 

Severity: error

The summary must not contain any URL. Use the `<url/>` tags for links.

summary-first-word-not-capitalized 

Severity: info

The summary text does not start with a capitalized word, project name or number.

summary-too-long 

Severity: warning

The summary text is very long, and will likely not be displayed properly everywhere.

icon-stock-cached-has-url 

Severity: error

Icons of type `stock` or `cached` must not contain an URL, a full or an relative path to the icon. Only file basenames or stock names are allowed.

icon-remote-no-url 

Severity: error

Icons of type `remote` must contain an URL to the referenced icon.

icon-remote-not-found 

Severity: warning

Unable to reach remote icon at the given web location - does it exist?

icon-remote-not-secure 

Severity: info

Consider using a secure (HTTPS) URL for the remote icon link.

metainfo-invalid-icon-type 

Severity: error

Metainfo files may only contain icons of type `stock` or `remote`, the set type is not allowed.

url-invalid-type 

Severity: warning

Invalid `type` property for this `url` tag. URLs of this type are not known in the AppStream specification.

url-not-reachable 

Severity: warning

Unable to reach remote location that this URL references - does it exist?

url-not-secure 

Severity: info

Consider using a secure (HTTPS) URL for this web link.

web-url-expected 

Severity: error

A web URL was expected for this value.

url-uses-ftp 

Severity: warning

This web link uses the FTP protocol. Consider switching to HTTP(S) instead.

url-redefined 

Severity: warning

An URL of this type has already been defined.

url-homepage-missing 

Severity: warning

This component is missing an `url` element of type `homepage` to link to the project's homepage.

developer-name-tag-deprecated 

Severity: info

The toplevel `developer_name` element is deprecated. Please use the `name` element in a `developer` block instead.

developer-info-missing 

Severity: info

This component contains no `developer` element with information about its author.

developer-id-missing 

Severity: info

The `developer` element is missing an `id` property, containing a unique string ID for the developer. Consider adding a unique ID.

developer-id-invalid 

Severity: warning

The developer-ID is invalid. It should be an rDNS string identifying the developer, or a Fediverse handle. It must also only contain lowercase ASCII letters, numbers and punctuation.

developer-name-missing 

Severity: warning

The `developer` block does not have a `name` element with a human-readable project author name.

developer-name-has-url 

Severity: warning

The `name` child of a `developer` block must not contain a hyperlink.

unknown-desktop-id 

Severity: error

The set value is not an identifier for a desktop environment as registered with Freedesktop.org.

launchable-unknown-type 

Severity: error

This `launchable` tag has an unknown type and can not be used.

bundle-unknown-type 

Severity: error

This `bundle` tag has an unknown type and can not be used.

update-contact-in-catalog-data 

Severity: warning

The `update_contact` tag should not be included in catalog AppStream XML.

nonstandard-gnome-extension 

Severity: info

This tag is a GNOME-specific extension to AppStream and not part of the official specification. Do not expect it to work in all implementations and in all software centers.

unknown-tag 

Severity: info

Found invalid tag. Non-standard tags should be prefixed with `x-`. AppStream also provides the <custom/> tag to add arbitrary custom data to metainfo files. This tag is read by AppStream libraries and may be useful instead of defining new custom toplevel or `x-`-prefixed tags if you just want to add custom data to a metainfo file.

metadata-license-missing 

Severity: error

The essential tag `metadata_license` is missing. A license for the metadata itself always has to be defined.

app-description-required 

Severity: error

The component is missing a long description. Components of this type must have a long description.

font-description-missing 

Severity: info

It would be useful to add a long description to this font to present it better to users.

driver-firmware-description-missing 

Severity: info

It is recommended to add a long description to this component to present it better to users.

generic-description-missing 

Severity: pedantic

This generic component is missing a long description. It may be useful to add one.

desktop-app-launchable-missing 

Severity: error

This `desktop-application` component is missing a `desktop-id` launchable tag. This means that this application can not be launched and has no association with its desktop-entry file. It also means no icon data or category information from the desktop-entry file will be available, which will result in this application being ignored entirely.

desktop-app-launchable-omitted 

Severity: info

This `desktop-application` component has no `desktop-id` launchable tag, however it contains all the necessary information to display the application. The omission of the launchable entry means that this application can not be launched directly from installers or software centers. If this is intended, this information can be ignored, otherwise it is strongly recommended to add a launchable tag as well.

console-app-no-binary 

Severity: warning

Type `console-application` component, but no information about binaries in $PATH was provided via a `provides/binary` tag.

web-app-no-url-launchable 

Severity: error

This `web-application` component is missing a `launchable` tag of type `url`.

web-app-no-icon 

Severity: error

This `web-application` component is missing a `icon` tag to specify a valid icon.

web-app-no-category 

Severity: warning

This `web-application` component is missing categorizations. A `categories` block is likely missing.

font-no-font-data 

Severity: error

Type `font` component, but no font information was provided via a `provides/font` tag.

driver-no-modalias 

Severity: warning

Type `driver` component, but no modalias information was provided via a `provides/modalias` tag.

extends-not-allowed 

Severity: error

An `extends` tag is specified, but the component is not of type `addon`, `localization` or `repository`.

addon-extends-missing 

Severity: error

The component is an addon, but no `extends` tag was specified.

localization-extends-missing 

Severity: info

This `localization` component is missing an `extends` tag, to specify the components it adds localization to.

localization-no-languages 

Severity: error

This `localization` component does not define any languages this localization is for.

service-no-service-launchable 

Severity: error

This `service` component is missing a `launchable` tag of type `service`.

metainfo-suggestion-type-invalid 

Severity: warning

Suggestions of any type other than `upstream` are not allowed in metainfo files.

category-invalid 

Severity: warning

The category name is not valid. Refer to the XDG Menu Specification for a list of valid category names.

all-categories-ignored 

Severity: warning

All categories for this component have been ignored, either because they were invalid or because they are of low quality (e.g. custom 'X-' prefixed or toolkit ones like 'GTK' or 'Qt'). Please fix your category names, or add more categories.

app-categories-missing 

Severity: error

This component is in no valid categories, even though it should be. Please check its metainfo file and desktop-entry file.

screenshot-caption-too-long 

Severity: info

The screenshot caption is too long (should be <= 100 characters)

file-read-failed 

Severity: error

Unable to read file.

xml-markup-invalid 

Severity: error

The XML of this file is malformed.

component-catalog-tag-invalid 

Severity: error

Invalid tag found in catalog metadata. Only `component` tags are permitted.

metainfo-ancient 

Severity: error

The metainfo file uses an ancient version of the AppStream specification, which can not be validated. Please migrate it to version 0.6 (or higher). Modern files use the `component` root tag and include many other differences, so check for changes carefully when modernizing the data.

root-tag-unknown 

Severity: error

This XML document has an unknown root tag. Maybe this file is not a metainfo document?

metainfo-filename-cid-mismatch 

Severity: warning

The metainfo filename does not match the component ID.

desktop-file-load-failed 

Severity: error

Unable to load the desktop-entry file associated with this component.

desktop-file-not-found 

Severity: warning

This component metadata refers to a non-existing .desktop file.

desktop-entry-category-invalid 

Severity: warning

A category defined in the desktop-entry file is not valid. Refer to the XDG Menu Specification for a list of valid categories.

desktop-entry-bad-data 

Severity: warning

Error while reading some data from the desktop-entry file.

desktop-entry-value-invalid-chars 

Severity: warning

The value of this desktop-entry field contains invalid or non-printable UTF-8 characters, which can not be displayed properly.

desktop-entry-value-quoted 

Severity: warning

This desktop-entry field value is quoted, which is likely unintentional.

desktop-entry-hidden-set 

Severity: warning

This desktop-entry file has the 'Hidden' property set. This is wrong for vendor-installed .desktop files, and nullifies all effects this .desktop file has (including MIME associations), which most certainly is not intentional.

desktop-entry-empty-onlyshowin 

Severity: warning

This desktop-entry file has the 'OnlyShowIn' property set with an empty value. This might not be intended, as this will hide the application from all desktops. If you do want to hide the application from all desktops, using 'NoDisplay=true' is more explicit.

dir-no-metadata-found 

Severity: info

No AppStream metadata was found in this directory or directory tree.

dir-applications-not-found 

Severity: pedantic

No XDG applications directory found.

metainfo-legacy-path 

Severity: warning

The metainfo file is stored in a legacy path. Please place it in `/usr/share/metainfo/`.

metainfo-multiple-components 

Severity: warning

The metainfo file specifies multiple components. This is not allowed.

releases-not-in-order 

Severity: warning

The releases are not sorted in a latest to oldest version order. This is required as some tools will assume that the latest version is always at the top. Sorting releases also increases overall readability of the metainfo file.

releases-type-invalid 

Severity: error

The type of the releases block is invalid. It needs to either `embedded` (the default) or `external`.

releases-url-insecure 

Severity: error

The URL to an external release metadata file is insecure. This is not allowed, please use HTTPS URLs only.

releases-download-failed 

Severity: error

Failed to download release metadata.

releases-external-not-found 

Severity: warning

A local release metadata file was not found. It is strongly recommended to validate this metadata together with the main MetaInfo file.

release-urgency-invalid 

Severity: warning

The value set as release urgency is not a known urgency value.

release-type-invalid 

Severity: warning

The value set as release type is invalid.

release-version-missing 

Severity: error

The release is missing the `version` property.

release-time-missing 

Severity: error

The release is missing either the `date` (preferred) or the `timestamp` property.

release-timestamp-invalid 

Severity: error

The release timestamp is invalid.

release-description-outside-tag 

Severity: error

The release description must be put inside a `description` tag

artifact-type-invalid 

Severity: error

The value set as artifact type is invalid. Must be either `source` or `binary`.

artifact-bundle-type-invalid 

Severity: warning

The value set as artifact bundle type is invalid.

artifact-invalid-platform-triplet 

Severity: warning

The platform triplet for this release is invalid. It must be in the form of `architecture-oskernel-osenv` - refer to the AppStream documentation or information on normalized GNU triplets for more information and valid fields.

artifact-checksum-type-invalid 

Severity: error

The selected checksumming algorithm is unsupported or unknown.

artifact-size-type-invalid 

Severity: error

The size type is unknown. Must be `download` or `installed`.

artifact-filename-not-basename 

Severity: error

The artifact filename must be a file basename, not a (relative or absolute) path.

release-issue-type-invalid 

Severity: error

The value set as release issue type is invalid.

release-issue-is-cve-but-no-cve-id 

Severity: warning

The issue is tagged at security vulnerability with a CVE number, but its value does not look like a valid CVE identifier.

releases-info-missing 

Severity: pedantic

This component is missing information about releases. Consider adding a `releases` tag to describe releases and their changes.

invalid-iso8601-date 

Severity: warning

The AppStream specification requires a complete, ISO 8601 date string with at least day-granularity to denote dates. Please ensure the date string is valid.

circular-component-relation 

Severity: warning

This component extends, provides, requires or recommends itself, which is certainly not intended and may confuse users or machines dealing with this metadata.

runtime-project-license-no-ref 

Severity: info

Licenses for `runtime` components are usually too complex to reflect them in a simple SPDX expression. Consider using a `LicenseRef` and a web URL as value for this component's `project_license`. E.g. `LicenseRef-free=https://example.com/licenses.html`

runtime-no-provides 

Severity: pedantic

Since a `runtime` component is comprised of multiple other software components, their component-IDs may be listed in a `<provides/>` section for this runtime.

unknown-provides-item-type 

Severity: info

The type of the item that the component provides is not known to AppStream.

mimetypes-tag-deprecated 

Severity: warning

The toplevel `mimetypes` tag is deprecated. Please use `mediatype` tags in a `provides` block instead to indicate that your software provides a media handler for the given types.

content-rating-missing 

Severity: info

This component has no `content_rating` tag to provide age rating information. You can generate the tag data online by answering a few questions at https://hughsie.github.io/oars/

content-rating-type-missing 

Severity: error

The `type` attribute of this `content_rating` element is missing or empty.

content-rating-type-invalid 

Severity: error

The `type` attribute of the `content_rating` element has an invalid value.

content-rating-invalid-tag 

Severity: error

The `content_rating` tag can only contain `content_attribute` children.

content-attribute-id-missing 

Severity: error

The `id` attribute of the `content_attribute` element is missing or empty.

content-attribute-id-invalid 

Severity: error

The `id` attribute of the `content_attribute` element has an invalid value.

content-attribute-value-empty 

Severity: error

The `content_attribute` tag needs a value.

content-attribute-value-unknown 

Severity: error

The `content_attribute` tag value is unknown.

content-attribute-value-invalid 

Severity: error

The `content_attribute` tag value is invalid for the given id.

content-attribute-id-duplicated 

Severity: error

A `content_attribute` tag with this ID has already been defined.

usertag-missing-namespace 

Severity: info

This `tag` is missing a `namespace` attribute.

usertag-invalid 

Severity: error

This tag or its namespace contains invalid characters. Only lower-cased ASCII letters, numbers, dots, hyphens and underscores are permitted.

branding-color-type-invalid 

Severity: error

The type of this color is not valid.

branding-color-scheme-type-invalid 

Severity: error

The value of this color scheme preference is not valid.

branding-color-scheme-wrong-property 

Severity: error

The name of the color scheme property is wrong. It should be `scheme_preference`.

branding-color-invalid 

Severity: error

This color is not a valid HTML color code.

branding-color-duplicated 

Severity: error

A color for this type/scheme combination was already set. Colors must be unique per type/scheme.

reference-doi-invalid 

Severity: warning

The given DOI (Digital Object Identifier) for this reference item is not valid.

reference-citation-url-invalid 

Severity: warning

The value for this citation reference item must be an URL to a CFF (Citation File Format) file.

reference-registry-name-missing 

Severity: error

This registry reference item is missing the `name` property to denote the name of the registry it is about.

reference-registry-name-unknown 

Severity: warning

The registry for this reference item is unknown. This may be due to a typing error, or the registry needs to be registered with AppStream.

reference-value-missing 

Severity: error

The reference item is missing a value.

custom-invalid-tag 

Severity: error

The `custom` tag can only contain `value` children.

custom-key-missing 

Severity: error

This `custom` tag value is missing a `key` attribute.

custom-key-duplicated 

Severity: error

A key can only be used once.

custom-value-empty 

Severity: info

This custom value is empty.

metainfo-localized-keywords-tag 

Severity: error

A `keywords` tag must not be localized in metainfo files (upstream metadata). Localize the individual keyword entries instead.