error 500 and key regeneration hangs

[JanuszU]

1. upgraded from version 2.1.27.36.

Expected behaviour

--

Actual behaviour

• after 5 users key regeneration , next regeneration hangs
• from time to time i get "error 500" as on picture

Server configuration

Operating system:
OracleLinux 9.4
Web server:
apache
Database:
MariaDB 10.11.8-MariaDB
PHP version:
8.2.19
Teampass version:
3.1.2.45
Teampass configuration file:

...
define("DB_ENCODING", "utf8");
...

Updated from an older Teampass or fresh install:
PLEASE attach to this issue the file /includes/config/tp.config.php.

Client configuration

Browser:
Chrome 125
Operating system:
Win11

Logs

Web server error log

Insert your webserver log here

Log from the web-browser developer console (CTRL + SHIFT + i)

Insert the log here and especially the answer of the query that failed.

[JanuszU]

there are no records now in "Task manager" - "Done" page ; there were some records before
could it get spoiled after I turned on the maintenance tasks ?!?