i have the same problem for around a year. jupyter lab3.

recently, annoyed by it. after study github serveral post and others. occasionally i noticed in the cmd shell output, i noticed it said

 [xxxx ServerApp] folder '' :my real work folder not found.

the address with additional '' & my work folder

[solution success]

jupyter lab config.py

c.LabServerApp.workspaces_dir = :my real work folder

pls noted no ' ' OR " " for the folder path.

others are default seting.

maybe it can solve your problem too?

refer:

reply from andrewfulton9 and echarles in https://github.com/jupyterlab/jupyterlab/issues/12111