Addon not running on FF 121.0 if gecko_android is in manifest?

I understood that the manifest should contain gecko and gecko_android if the addon runs on both platforms.

If I add gecko_android and try to load the addon as temp (about:debugging#/runtime/this-firefox), it is refused:

Reading manifest: Error processing applications: Property “gecko_android” is unsupported by Firefox

FF on Win 11, version 121.0.

What am I doing wrong?

thanks, Klaus

Could you post your manifest file here?
In any case, here is an example of how it should look:

  "browser_specific_settings": {
    "gecko": {
      "id": "admin@abc.com_MyAddon",
      "strict_min_version": "115.0"
    "gecko_android": {
      "strict_min_version": "115.0"

More info in the docs:


thanks, that is how my manifest file is.
In another forum (probably element?), I got the answer that at that time the temp install did not recognise the android entry

@opto, based on the error message you shared it appears that you’re trying to set "gecko_android" on the "applications" key in your extension manifest rather than "browser_specific_settings".

Firefox used to use "applications" in the manifest (and still does internally), but that value was dropped in favor of "browser_specific_settings" several years ago and no longer appears on the list of supported manifest keys.

thanks, I figured that out already by MDN docu.