Unfortunately, everything is the same as before. Thank God I have VM-Ware and snapshots, plus a replica of my active mail server. So I can try things out completely relaxed. 18:30 rollback to 2026-01, login with LDAP users works, update again to 2026-03. The error is there again. Picture-1 and control test login with local admin and user works, The Blacked is only the Log-In Credentials.

Function check of the LDAP connection - see picture 2 = OK. So a few mailboxes I deleted manually, LDAP query reduced to 10 minutes - and waited… No false “all good” message, after that time the missing mailboxes were recreated from the ADC. So the LDAP access must work properly.

And so my active MailCow will remain at the January level :-)