Mailboxes on a recently recovered multirole (Client Access and Mailbox) server that is running Microsoft Exchange Server 2013 cannot access the free/busy service.
When this problem occurs, the following errors are logged.
Outlook logs (Outlook.etl files):
Recipient: firstname.lastname@example.org Exception: Proxy web request failed. , inner exception: The request failed with HTTP status 404: Not Found. Server Name: < problematic server> Exception Type: ProxyWebRequestProcessingException Response Code: ErrorProxyRequestProcessingFailed
Use ADSIEdit to change the InternalNLBBypassUrl value for EWS for this problematic server. Then, recycle the MSExchangeServicesAppPool application pool in IIS. After you recycle the application pool, EWS should work as expected.
Use Windows PowerShell to change these settings.
Note Window PowerShell returns a “not within a valid server write scope” error message.
Start Windows PowerShell.
Add the Exchange snap-in. To do this, run the following command:
Run the following command:
Set-WebServicesVirtualDirectory -Identity "<problematic server>\EWS (Exchange Back End)" -InternalNLBBypassUrl https://<FQDN of the problematic server>:444/ews/exchange.asmx