Operating system: Windows-10-10.0.16299 64 Bits
Graphics card: GeForce GTX 1080/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 419.67
Broken: version: 2.80 (sub 72), branch: blender2.7, commit date: 2019-05-29 18:17, hash: rBfee600f47980
Short description of error
Open attached file.
Convert selected bezier curve to mesh (Object > Convert to). A menu will pop up.
Select "Keep original". Menu disappears and a mesh was created.
Select original bezier curve again. Convert it to mesh once more. Now the menu is gone and you can't bring it back with a F9 hotkey.