Help with Supabase + Facebook OAuth Error

I’m implementing Facebook authentication with Supabase in my Bubble app and getting this error on the callback:

error=server_error&error_code=unexpected_failure&error_description=Unable to exchange external code

My setup:

  • Supabase project with Facebook provider enabled
  • Facebook app configured with OAuth redirect to Supabase’s callback URL
  • Bubble app that initiates the flow and handles the callback

What I’ve tried:

  • I’ve tested with both my custom domain and the default Bubble domain prefix
  • I’ve ensured consistent domain usage across all platforms for each test
  • Verified my callback URLs match exactly between all three platforms
  • Double-checked all Facebook app settings and Supabase configurations

I noticed that Facebook seems to handle URL formatting differently than Google. When I paste my authorization URL into Facebook’s Valid OAuth Redirect URIs, it automatically transforms and encodes the URL in a specific way, which might be causing compatibility issues with Supabase.

Important note: I successfully implemented Google authentication using the same approach. So my general Supabase auth setup seems correct, but something specific to the Facebook implementation isn’t working.

Has anyone successfully implemented Supabase + Facebook auth with Bubble? Are there any known issues or special considerations for Facebook specifically?

I’d appreciate any insights or working examples. Thanks!

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