[Solved] 'object reference not set to an instance of an object' when editing users without mailboxes

We’re getting the error message ‘object reference not set to an instance of an object‘ when trying to edit a user without a mailbox. 
We’re not sure since when this error exists because there aren’t many users without mailboxes. 

But two weeks ago we updated cloudpanel to the latest version and manly started to notice the errors, so there could be a connection.

The logs look like this:

2022-12-12 09:19:03,345 [ERROR] CloudPanel.Modules.CompanyModules.UsersEditModule – Error updating user values: System.NullReferenceException: Der Objektverweis wurde nicht auf eine Objektinstanz festgelegt.
bei CloudPanel.ActiveDirectory.ADUsers.UpdateUser(Users userObject)
bei CloudPanel.Modules.CompanyModules.UsersEditModule.<>c__DisplayClass1_0.<.ctor>b__37(Object _)

What’s also weird is that the changes are transfered to the active directory, but not to the cloudpanel database.