Linter Rules

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Rules are sorted by severity.


Message code Severity Description
KNOWN_LIBRARY notice This is version of a JS library is known and generally accepted.
OPENDIALOG_NONLIT_URI notice openDialog called with non-literal parameter.
UNEXPECTED_GLOGAL_ARG warning Unexpected global passed as an argument.
NO_IMPLIED_EVAL warning disallow the use of eval()-like methods.
OPENDIALOG_REMOTE_URI warning openDialog called with non-local URI.
NO_DOCUMENT_WRITE warning Use of document.write strongly discouraged.
JS_SYNTAX_ERROR warning JavaScript compile-time error.
UNADVISED_LIBRARY warning This version of a JS library is not recommended.
DEPRECATED_API warning API is deprecated.
STORAGE_SYNC warning Temporary IDs can cause issues with storage.sync.
STORAGE_MANAGED warning Temporary IDs can cause issues with storage.managed.
IDENTITY_GETREDIRECTURL warning Temporary IDs can cause issues with identity.getRedirectURL.
RUNTIME_ONMESSAGEEXTERNAL warning Temporary IDs can cause issues with runtime.onMessageExternal.
RUNTIME_ONCONNECTEXTERNAL warning Temporary IDs can cause issues with runtime.onConnectExternal.
BANNED_LIBRARY error This version of a JS library is banned for security reasons.
INCOMPATIBLE_API warning API not compatible with applications.gecko.strict_min_version
ANDROID_INCOMPATIBLE_API warning API not compatible with Firefox for Android at applications.gecko.strict_min_version



Message code Severity Description
CSS_SYNTAX_ERROR error A CSS syntax error was detected.
INVALID_SELECTOR_NESTING error CSS selectors should not be nested.


Message code Severity Description
INLINE_SCRIPT warning Inline script is disallowed by CSP.
REMOTE_SCRIPT warning Remote scripts are not allowed as per Add-on Policies.


Message code Severity Description
HIDDEN_FILE warning Hidden file flagged.
FLAGGED_FILE warning Flagged filename found.

Package layout

Message code Severity Description
MOZILLA_COND_OF_USE notice Mozilla conditions of use violation.
FLAGGED_FILE_TYPE notice (Binary) Flagged file type found.
FLAGGED_FILE_EXTENSION warning Flagged file extensions found
ALREADY_SIGNED warning Already signed
COINMINER_USAGE_DETECTED warning Firefox add-ons are not allowed to run coin miners.
DUPLICATE_XPI_ENTRY error Package contains duplicate entries.
INVALID_XPI_ENTRY error Package contains invalid entries (e.g. invalid characters in entries path name).
BAD_ZIPFILE error Bad zip file.
FILE_TOO_LARGE error File is too large to parse
RESERVED_FILENAME error Reserved filename detected.

Type detection

Message code Severity Description
TYPE_NO_MANIFEST_JSON notice Add-on missing manifest_json for type detection.

Language packs

Message code Severity Description
FLUENT_INVALID warning Invalid fluent template file.

Web Extensions / manifest.json

Message code Severity Description
MANIFEST_UNUSED_UPDATE notice update_url ignored in manifest.json
CORRUPT_ICON_FILE warning Icons must not be corrupt
MANIFEST_CSP warning content_security_policy in manifest.json means more review
MANIFEST_CSP_UNSAFE_EVAL warning usage of 'unsafe-eval' is strongly discouraged
MANIFEST_PERMISSIONS warning Unknown permission
MANIFEST_OPTIONAL_PERMISSIONS warning Unknown optional permission
MANIFEST_HOST_PERMISSIONS warning Unknown host permission
NO_MESSAGES_FILE warning When default_locale is specified a matching messages.json must exist
NO_DEFAULT_LOCALE warning When _locales directory exists, default_locale must exist
UNSAFE_VAR_ASSIGNMENT warning Assignment using dynamic, unsanitized values
UNSUPPORTED_API warning Unsupported or unknown browser API
DANGEROUS_EVAL warning eval and the Function constructor are discouraged
STRICT_MAX_VERSION warning strict_max_version not required
PREDEFINED_MESSAGE_NAME warning String name is reserved for a predefined
MISSING_PLACEHOLDER warning Placeholder for message is not
MANIFEST_FIELD_PRIVILEGEDONLY warning A manifest field ignored on non-privileged extensions
MANIFEST_FIELD_UNSUPPORTED warning A manifest field is not supported (or not supported for the extension manifest_version)
MANIFEST_PERMISSION_UNSUPPORTED warning A manifest permission is not supported for the extension manifest_version
MANIFEST_PERMISSIONS_PRIVILEGED error A manifest permission is only allowed in privileged extensions
MOZILLA_ADDONS_PERMISSION_REQUIRED error The "mozillaAddons" permission must be specified in privileged extensions
PRIVILEGED_FEATURES_REQUIRED error Privileged features are mandatory for privileged extensions, but none has been detected
MANIFEST_FIELD_PRIVILEGED error A manifest field is only allowed in privileged extensions
WRONG_ICON_EXTENSION error Icons must have valid extension
MANIFEST_UPDATE_URL error update_url not allowed in manifest.json
MANIFEST_FIELD_REQUIRED error A required field is missing
MANIFEST_FIELD_INVALID error A field is invalid
MANIFEST_FIELD_DEPRECATED error A field is deprecated
MANIFEST_BAD_PERMISSION error Bad permission
MANIFEST_BAD_OPTIONAL_PERMISSION error Bad optional permission
MANIFEST_BAD_HOST_PERMISSION error Bad host permission
MANIFEST_INSTALL_ORIGINS error Invalid install_origins
JSON_BLOCK_COMMENTS error Block Comments are not allowed in JSON
MANIFEST_INVALID_CONTENT error This add-on contains forbidden content
CONTENT_SCRIPT_NOT_FOUND error Content script file could not be found
CONTENT_SCRIPT_EMPTY error Content script file name should not be empty
NO_MESSAGE error Translation string is missing the message
INVALID_MESSAGE_NAME error String name contains invalid characters
INVALID_PLACEHOLDER_NAME error Placeholder name contains invalid characters
NO_PLACEHOLDER_CONTENT error Placeholder is missing the content
JSON_INVALID error JSON is not well formed
JSON_DUPLICATE_KEY error Duplicate key in JSON
MANIFEST_VERSION_INVALID error manifest_version in manifest.json is not valid
PROP_NAME_MISSING error name property missing from manifest.json
PROP_NAME_INVALID error name property is invalid in manifest.json
MANIFEST_DICT_NOT_FOUND error A dictionary file defined in the manifest could not be found
MANIFEST_MULTIPLE_DICTS error Multiple dictionaries found
MANIFEST_EMPTY_DICTS error Empty dictionaries object
MANIFEST_DICT_MISSING_ID error Missing property for a dictionary
KEY_FIREFOX_UNSUPPORTED_BY_MIN_VERSION warning Manifest key not compatible with applications.gecko.strict_min_version
KEY_FIREFOX_ANDROID_UNSUPPORTED_BY_MIN_VERSION warning Manifest key not compatible with Firefox for Android at applications.gecko.strict_min_version
PERMISSION_FIREFOX_UNSUPPORTED_BY_MIN_VERSION notice Permission not compatible with applications.gecko.strict_min_version
PERMISSION_FIREFOX_ANDROID_UNSUPPORTED_BY_MIN_VERSION notice Permission not compatible with Firefox for Android at applications.gecko.strict_min_version
IGNORED_APPLICATIONS_PROPERTY warning Usage of both applications and browser_specific_settings properties
RESTRICTED_HOMEPAGE_URL error Linking to in homepage_url or developer.url is not allowed
RESTRICTED_PERMISSION error A permission requires "strict_min_version" to be set to a specific Firefox version
EXTENSION_ID_REQUIRED error The extension ID is mandatory for Manifest Version 3 (and above) extensions
HIDDEN_NO_ACTION error The hidden and browser_action/page_action (or action) properties are mutually exclusive
APPLICATIONS_DEPRECATED warning The applications property in the manifest is deprecated and will no longer be accepted in Manifest Version 3 and above. Use browser_specific_settings instead.
APPLICATIONS_INVALID error The applications property is no longer accepted in Manifest Version 3 and above.
VERSION_FORMAT_DEPRECATED warning The version string should be simplified.
VERSION_FORMAT_INVALID error The version string is not valid because its format is too complex.

Static Theme / manifest.json

Message code Severity Description
MANIFEST_THEME_IMAGE_MIME_MISMATCH warning Theme image file extension should match its mime type
MANIFEST_THEME_IMAGE_NOT_FOUND error Theme images must not be missing
MANIFEST_THEME_IMAGE_CORRUPTED error Theme images must not be corrupted
MANIFEST_THEME_IMAGE_WRONG_EXT error Theme images must have one of the supported file extensions
MANIFEST_THEME_IMAGE_WRONG_MIME error Theme images mime type must be a supported format
MANIFEST_THEME_LWT_ALIAS error Theme LWT aliases are deprecated