Yoyogames docs states the following: The following section refers to obsolete functions that were only valid for the old GameMaker: Studio 1.4 legacy Facebook extension. As such you can no longer use these functions in your projects. For current Facebook functionality you need to have activated the Facebook API in the appropriate Game Options for the target platform, which will prompt you to download and install the extension. The extension comes with a *.pdf format mini-manual explaining how to use it as well as showing all the function definitions and examples. All references to the old facebook_*() functions will need to be replaced (and updated) to use the extension fb_*() equivalents. I did the above and it prompted me to download Facebook Extension for GM 1.4 (nothing on 2.0). Couldn't find any pdf. When build it just throws a list of errors like the following Script: Firebase_Facebook_signIn at line 6 : unknown function or script facebook_login Same result even if I tried with fb_login. Am I missing something or this is a GM2 bug? Btw, I am running GM 184.108.40.2063 Kindly advise. Thanks.