On 23 Mar 2021, HSM said the following...

PYTHON ERROR (mysticbb.mpy) File "mysticbb.mpy", line 71, in <module ImportError: No module named mysticbb_cfg

So it's looking for a mysticbb_cfg file, create one with notepad or the like. It can have nothing in it if it's just looking for the file, it might want to write to it (initial configuration).It does sound like a file protection
issue (attrib +r +w mysticbb_cfg) or more likely issues with mysticbb,mpy ownership. Check Properties on the file for attributes and owner vis mystic.dat for example.

--- Mystic BBS v1.12 A47 2021/02/12 (Raspberry Pi/32)
* Origin: Mystic Pi BBS bcw142.zapto.org (21:1/145)