Outlook Web App couldn't initialize. Invalid forms registry file %1 Line number = %2 Position = %3. The value "%4" specified ...

Outlook Web App couldn't initialize.

Invalid forms registry file %1  Line number = %2  Position = %3. The value "%4" specified for the ClientControl element isn't one of the expected values.

The forms registry is a critical component of Outlook Web App. If this error isn't addressed, users might not be able to access Outlook Web App. The Help and Support Center provides information about how to troubleshoot the forms registry.