Hi you
I have two very bad problem with userman
the first is about when i try to delete a user I get the error of "Operation Failed" picture attached
the second and really annoying one is that the userman sometimes delete users itself
and i literally don't have any idea what to do with them there are 3 different server all having this issue
userman working on x86 6.49.2
looking forward any solution or help

It's only your problem.

First of all, why not using the latest 6.49.8, but a two year old version?
Maybe on newer versions, there was a bug, they fixed it.

I've had usermanager 6.x for years on various machines and versions and never had any such bugs.

You have indicated absolutely nothing concrete, useful, or remotely necessary to understand the problem, except the RouterOS version.
Your post is completely useless without the export and the database.

sorry for inconvenience
BUT
I cannot post my DB or full Export
and if I'm doing somewhere wrong it could not be the only me and other users must have the same problem

i also tried 6.49.8 but no changes

and if I'm doing somewhere wrong it could not be the only me and other users must have the same problem

So if you make a mistake or have a problem, does anyone else have to make the same mistake or have the same problem as you?
Maybe others don't make the same mistakes as you and don't use the devices you're using, which maybe are the ones causing the problem.