A Veeam Backup for Office 365 job fails with a timeout error.  

These commonly are reported as one of the the following errors:

  • Unexpected End of File
  • Exchange Web Services error code: ErrorExceededConnectionCount
  • Error: Failed to get folder properties
  • Error: You have exceeded the available concurrent connections for your account.  Try again once your other requests have completed.
  • Error: Unexpected end of file has occurred. The following elements are not closed: m:Data, m:ExportItemsResponseMessage, m:ResponseMessages, m:ExportItemsResponse, s:Body, s:Envelope. Line 1, position 21397505.
But are not limited to these errors.



There are multiple causes for these timeout errors.  The most common being a bad connection to the Exchange Web Service (EWS) from the Veeam Backup for Office 365 server or proxy.  This can be caused by a flooding of open worker threads to the Exchange Web Services server, network traffic saturating the throughput of the connection, a slow internet connection to the Office 365 EWS server amongst other issues.


In 1.5, performance settings to help with timeout errors can be adjusted through the proxy performance settings (Concurrent Threads, and limit network bandwidth).