When ActiveSync in Exchange Server 2010 becomes inoperable due to unknown reason, other applications that are linked up with Active Sync may become non-functional as well. In my case, I have stumbled upon where smart devices stopped synchronizing to Exchange Server 2010, Outlook Web App (OWA), Exchange Management Console (EMC) and Internet Information Services (IIS) also became inoperable. Note that Microsoft Outlook is fully operational.
- Navigate to C:\Windows\System32\inetsrv\config, locate applicationHost.config and rename to applicationHost.config.old
- Replace the file C:\Windows\System32\Inetsrv\Config\Applicationhost.config from a backup.
- Open a command prompt and run iisreset to Reset the IIS Service.
Now, test the email flow from a smartphone. Access the OWA, open up EMC and IIS. They should all start working and be fully functional.