I get these two errors after upgrading to DOTS 0.50:
Library\PackageCache\com.unity.entities@0.50.0-preview.24\Unity.Entities.Hybrid\GameObjectConversion\GameObjectConversionMappingSystem.cs(1093,36): error CS0030: Cannot convert type 'Unity.Entities.Chunk.<Buffer>e__FixedBuffer' to 'Unity.Entities.Entity*'
Library\PackageCache\com.unity.entities@0.50.0-preview.24\Unity.Entities.Hybrid\GameObjectConversion\GameObjectConversionMappingSystem.cs(1099,52): error CS0019: Operator '+' cannot be applied to operands of type 'Chunk.<Buffer>e__FixedBuffer' and 'int'
Actually, after restarting I got other errors pointing to the one remaining (missing) reference, since I was in the process of adding references to an assembly definition when the errors inside com.unity.entities appeared.