When you use Outlook Web Access (OWA) in light mode in a shared mailbox in an Exchange Server 2010 environment, you cannot run a search, and you receive the following error message:
Your request couldn't be completed. This may have occurred for security reasons or because your session timed out.
Additionally, the following error is logged in the Application event log:
Exception: Type: Microsoft.Exchange.Clients.Owa.Core.OwaInvalidCanaryException Error: Invalid canary in search query.
Note This issue occurs only in Update Rollup 15 and Update Rollup 16 for Exchange Server 2010 Service Pack 3.