WebExtension with Native Messaging

I have looked over the MDN, but could not find the answer to this question: which Firefox versions support WebExtensions AND Native Messaging?

I am asking this because I have a Firefox extension, on the Web Store, which uses Native Messaging. I have performed the following checks under Windows 8.1 x64, for Firefox 55:

  • registry key present in “HKEY_LOCAL_MACHINE\SOFTWARE\Mozilla\NativeMessagingHosts\my.msg.host” so no Wow6432 key). “my.msg.host” is not the actual name, it’s just an example.
  • path to JSON present in the key above. The JSON file is accessible by “Everyone” in the Windows Security context.
  • the JSON has the doubled backslashes in the path and the allowed extension ID is correct.

Although my extension attempts to start the NMH, Firefox 55 does not start it. I have used Process Monitor and Firefox 55 does not even read the “NativeMessagingHosts” registry key. What am I doing wrong?

It should have been present in Firefox since version 50, according to this bug.

I have found the problem: the JSON listed “Background.js”, but the file name was “background.js”, with a lowercase “b”. The funny thing is that Firefox displays no warning in the console.

That’s it, thanks for the advice @jorgev!