Yesterday I had a little problem with Office Web Apps 2010. After a manual installation in the farm, Word and PowerPoint files viewed fast and nice inside the browser. But.. Excel files said: “The workbook cannot be opened”. Okei…-must be something wrong with the files, I uploaded a test file from my SkyDrive,  nope, same error…

Like lightning it struck me :-), off course! –the managed service account. I created in AD for the Excel Service app, it doesn’t`t have any schemas in SQL content_db. In the old days (read 2007) you would provide this manually in SQL manager.

Today we have PowerShell for this 🙂

PS> $w = Get-SPWebApplication –Identity <URL of the Web application>
PS> $w.GrantAccessToProcessIdentity("<insert service account>")

It works like a charm after IISreset –noforce

http://support.microsoft.com/kb/981293