Issue Migration problem with roundcube 1.6.9

[kristobal1969]

Server operating system version

Ubuntu 22.04.5 LTS

Plesk version and microupdate number

Plesk 18.0.64 #1

Hi,
Problem with roundcube 1.6.9 : I have juste migrated my old server with plesk 18.0.64 on Debian 10.13 to another server on plesk 18.0.64 on Ubuntu 22.04.5 LTS and I have a problem with one of my mail account on one domains whose mail account is near 17Go with many folders and sub-folders... When using Horde that is really so old !!! I have no problems but looks not cool at all.

When login to the webmail I got this message.

Internal Server Error​

The server encountered an internal error or misconfiguration and was unable to complete your request.
Please contact the server administrator at [no address given] to inform them of the time this error occurred, and the actions you performed just before this error.
More information about this error may be available in the server error log.

I manage to open the webmail by pressing the back button of the navigator and can see the messages and navigate but it is not coool at all.

I manage to got to parameters and I see that the special folder seems to be the responsible of the problem (see screen shot).
Does anybody know how to make it work correctly ? May be a problem of memory ? I think I did that in the old Debian but I do not remember.
Hope you can help me. May be it is something else !
Regards
Kris