“Error: Specified argument was out of the range of valid values.” in SharePoint Online and OneDrive for business backup jobs.

Challenge

SharePoint Online and/or OneDrive backup jobs fail with the following error:
 

25/07/2018 10:05:17 PM   61 (6188) Error: Specified argument was out of the range of valid values.
25/07/2018 10:05:17 PM   61 (6188) Type: System.ArgumentOutOfRangeException
25/07/2018 10:05:17 PM   61 (6188) Stack:
25/07/2018 10:05:17 PM   61 (6188)    at Microsoft.SharePoint.Client.ChunkStreamBuilder.ReadonlyChunkStream.set_Position(Int64 value)

Cause

Due to a bug in SharePoint Online API, incorrect length of a file is returned to Veeam Backup for Microsoft Office 365 during a backup job run. This results in treating an EOF marker as an ungraceful termination of a download stream and initiating a retry from the last good position. Since the last good position is, in fact, an EOF marker, a read request is issued with an argument which is out of the range of valid values.

Solution

While a bug in SharePoint Online API is yet to be fixed by Microsoft, a hotfix with improved handling of such situations is already available for Veeam Backup for Microsoft Office 365. To get it, please contact Veeam technical support.