Unable to connect to the Cinnamon Spices server

[Hilyxx]

Recently, it has become impossible to connect to the Cinnamon Spices server. A dialog box appears with the following error message:

TypeError: int() argument must be a string, a bytes-like object or a real number, not 'NoneType'

The same error occurs even in a virtual machine, so it doesn't appear to be caused by my local setup or by a broken package on my end.

@mtwebster, do you have any idea what might be causing this issue?

[Hilyxx]

see linuxmint/cinnamon#13868 (comment)