Had this issue quit some time in my test environment, but never had the time nor the mood to resolve the issue.
OWA works fine for normal e-mail usage, but when you try to set some options, rules a pop-up is displayed which say OWA encountered an unexpected error.
Troubleshooting the issue showed me that the Exchange Control Panel was also unreachable. When accessing Owa from the internet (public url), only the error was displayed with no further information. When trying to access the ECP from the private interface, i managed to retrieve more information on the error "EventID: 4, source: MSExchange Control Panel".
The next logical step is to check the eventvwr, where i discovered that the following event was logged each time i reproduced the issue:
Performance counter updating error. Counter name is Total time for saving Admin Audit records, category name is MSExchange Admin Audit. Optional code: 1. Exception: The exception thrown is : System.InvalidOperationException: The requested Performance Counter is not a custom counter, it has to be initialized as ReadOnly.
I decided to try my luck on the Internet which led me to following tech-net forum-post:
The solution provided in the forum did resolve the issue.
Open the command prompt in administrative modus, which starts by default in the %systemroot%\system32 folder. If not, go to that path and run following command:
LODCTR /r (resets the performance counters)
IISRESET /noforce (restart the IIS services)
more info on LODCTR can be found here: