Post migration of a working PowerPivot system from Windows authentication to claims authentication sometimes not all workbook files author property is updated to the new format, this causes the "PowerPivot Management Dashboard Processing Timer Job" to fail with error:
“Microsoft.SharePoint.SPException: User cannot be found” at Microsoft.AnalysisServices.SPAddin.UsageProcessingTimerJob.PrepareUsageData
Some or all of your PowerPivot files like have their author property set in the old Windows style name like “MYDOMAIN\someuser”
If the author property was set to a claims format the error would go away, like “i:0#.w|MYDOMAIN\someuser”
The workaround for this issue is to delete and re-upload the PowerPivot workbooks affected.
The author field can not be fully examined from the SharePoint UI, so it can be difficult to track down all of these workbooks.
Attached to this post is sample code that shows one way to list all of the workbooks for a Site Collection that have an author property in the Windows style format (these files will throw and error when the "PowerPivot Management Dashboard Processing Timer Job" runs).
** THIS SAMPLE CODE IS PROVIED AS IS, WITH NO WARRANTEES OR SUPPORT OF ANY KIND, USE AT YOUR OWN RISK **
The .exe must be ran from one of the farm SharePoint 2013 servers
The output is tab delimited so you can open with Excel to sort and filter as needed
useage: ScanSPAuthor <SiteColUrl>example: ScanSPAuthor http://warrenr-ws1/sites/SC1output at C:\temp\AuthorReport.txt
error and diag log at C:\temp\AuthorReportError.txt