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Introducing the new Universal Render Pipeline and High Definition Render Pipeline subforums!
Unity 2019.3 Beta is out now.
For others facing this issue:
17276: [Unity] Assembly 'Assets/FacebookSDK/Plugins/Facebook.Unity.dll' will not be loaded due to errors:
To add some context to what studentutu is trying to do, it appears that Unity 2019.2.0f1 always tries to compile against Facebook SDK...
I just tested in 2018.3.12f1 and it still appears to be broken. Same issue: dyld: Symbol not found: _UnitySendMessage.