Exchange UM: “Sorry, a system error has occurred.”

Posted by in Exchange, Lync, OCS

Today our UM server suddenly started giving an error when people tried to leave a voicemail. The error said:

“Sorry, a system error has occurred. Please try again later.”

No changes had been made to Lync or the UM environment for sometime.

In the event log I noticed the following events:

Event 1078, MSExchange Unified Messaging

Event 1078

Event 1159, MSExchange Unified MessagingThe key piece of information here is the Unable to load DLL ‘WMVCore.dll’: The specified module could not be found. (Exception from HRESULT: 0x8007007E) error.

Event 1159

A quick Google of the WMVCore.dll error revealed that this DLL came along with the Desktop Experience feature in Windows and would have been installed as part of the UM role. When I compared the installed features against another Exchange server with the UM role I noticed that this feature was missing.The call with ID “xxxxxxxxxxxxxxxxxxxxxxxxxxxx” was disconnected by the Unified Messaging server because of a system error.

It turns out that my Infrastructure team decided the Desktop Experience feature was not allowed on servers for whatever reason and they had removed it.

After the feature was re-installed and the server was rebooted voicemail began to work again.