System Information
Operating system: Windows-10-10.0.18362 64 Bits
Graphics card: Intel(R) HD Graphics Intel 4.3.0 - Build 20.19.15.4835

Blender Version
Broken: version: 2.81 (sub 1), branch: master, commit date: 2019-08-03 10:22, hash: rB5e5cf9ea9f7b
Worked: (optional)

Short description of error
[Please fill out a short description of the error here]
add curve … edit mode works … convert to mesh … enter edit mode … fails …. this happens with all objects in edit mode
Exact steps for others to reproduce the error
[Please describe the exact steps needed to reproduce the issue]
[Based on the default startup or an attached .blend file (as simple as possible)]