System Information
Operating system: Windows-10-10.0.19041-SP0 64 Bits
Graphics card: NVIDIA GeForce RTX 2070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 471.41

Blender Version
Broken: version: 2.90.0, branch: master, commit date: 2020-08-31 11:26, hash: rB0330d1af29c0
Worked: (newest version of Blender that worked as expected)

Addon Information
Name: FBX format (4, 21, 3)
Author: Campbell Barton, Bastien Montagne, Jens Restemeier

No errors now. Somehow everything works)