OAuth UST not work

Hello team!
We have migrated from JWT to OAuth Server-to-Server. After the migration, we updated the User sync tool to v2.9.0rc2. We also corrected the UMAPI settings according to the instructions. When starting UST, we get an error.

2023-06-25 21:29:46 13192 INFO main - ========== Start Run (User Sync version: 2.9.0rc2) ===================
2023-06-25 21:29:46 13192 INFO main - User Sync 2.9.0rc2 - Python 3.9.13 - Windows 10.0.17763
2023-06-25 21:29:46 13192 INFO main - ------- Command line arguments -------
2023-06-25 21:29:46 13192 INFO main - --users mapped --process-groups
2023-06-25 21:29:46 13192 INFO main - -------------------------------------
2023-06-25 21:29:46 13192 CRITICAL main - Unhandled exception
Traceback (most recent call last):
File "user_sync\app.py", line 461, in run_sync
File "user_sync\app.py", line 398, in begin_work_umapi
File "user_sync\connector\connector_umapi.py", line 73, in __init__
TypeError: argument of type 'NoneType' is not iterable
2023-06-25 21:29:46 13192 INFO main - ========== End Run (User Sync version: 2.9.0rc2) (Total time: 0:00:00)

Accordingly, the transfer of users does not work. Any idea what we're doing wrong?