System Information
Operating system: Linux-5.0.0-36-generic-x86_64-with-debian-buster-sid 64 Bits
Graphics card: GeForce GTX 1060 6GB/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 430.26

Blender Version
Broken: version: 2.81 (sub 16), branch: master, commit date: 2019-11-18 12:53, hash: rB115a5bf65a6b
Worked: (optional)

Short description of error
Unable to upload an asset to blenderkit. It's uploading metadata but after that, it stops by printing b"'Object' object has no attribute 'blenderkit'\n" 50 in the console as well as OpenGL UI

Exact steps for others to reproduce the error
Try to upload a model using Blenderkit add-on. It uploads metadata but after that, it stops by printing above message in UI and console.