Any more ideas?

i have exactly same issue.

I can't remove newly created user, even without mailbox. I raised logging level to 4 and don't see any errors in SolidCP log on domain controller. So this is not misconfigration of system.

Also i discovered, when you choose remove user, promt confirmation windows doesn't appear, but it should. I just see continuously running "Please wait..." message. So i think this is some internal issue of Server component of SolidCP website.

Any help?

What version of server are you using? What version of Exchange ?

Exchange 2016, Manage panel use Windows Server 2016

After running windows, sometimes appear error

System.Web.Services.Protocols.SoapException: Server was unable to process request. ---> System.Exception: Error executing 'REMOVE_USER' task on '' ORGANIZATION ---> System.NullReferenceException: Object reference not set to an instance of an object. at SolidCP.EnterpriseServer.OrganizationController.DeleteUser(Int32 itemId, Int32 accountId)