I have https enabled and followed the Google account login tutorial. Now everything works until I select the Google account that I wish to sign in with. Then I receive a 403 error on the https://mysite.com/store/oauth/callback/?very_long_api_key*
Currently the app's publishing status is product and user type is external. Also, the Authorized redirect URI within the Client ID settings matches what is shown in the ACP.

I have doubled checked everything and am not sure what could be causing this. Any help would be appreciated!

*Keep in mind this arbitrary text.

The 403, please could you clarify if thats showing from googles side or your side? (Is it a google page?) It sounds very much like its coming from your server direct, so I would suggest making sure you check your server error logs, and anything like mod_security that is on the server, as the server itself is denying the request

 

The 403, please could you clarify if thats showing from googles side or your side? (Is it a google page?) It sounds very much like its coming from your server direct, so I would suggest making sure you check your server error logs, and anything like mod_security that is on the server, as the server itself is denying the request

Yeah it is coming from my server, now I did run into a similar issue when trying to enable zapier and received the following error:
" Zapier needs to use the REST API to communicate with your community, but there is currently an issue with your REST API setup. Visit the REST & OAuth page to learn more and fix this issue."  

Could there two issues be related or are they entirely separate? 

Its very likely they may be related yes. As mentioned, I would check your server error logs at this point to determine exactly what is causing the 403