… on the SharePoint 2010 with german system language of my customer the message text was “Fehler bei PowerPoint Web App. Wiederholen Sie den Vorgang.”

In the SharePoint log I found this lines:

First: “Could not find default ServiceProxy or it does not implement IWacServiceApplicationProxy”

Second: “Unhandled exception caught when executing web method handler: System.NullReferenceException”

The Solution:

There was a missing setting for the Service Application Default Proxy Group

Go to: Central Administration –> Application Management –> Configure service application association  ==> click the link (e.g. “default”) in column “Application Proxy Group” of your web application.

You should see something like that:

Check the missing proxy. Click OK. That’s it…

Today I got this error while opening a Word document stored in a SharePoint library. This document should be opened in the Word Web App. – IT WAS A DOCUMENT IN A MIGRATED CONTENT DATABASE…

(“Word Web App cannot open this document for viewing because of an unexpected error. To view this document, open it in Microsoft Word.”)

I looked into SharePoint log and found this error message:

(“Requesting item that was not generated”)

Then I looked into Windows Event Viewer and found this critical error event:

(“SQL Database ‘…’ on SQL Server instance ‘…’ not found. Aditional error information from SQL Server is included below.” … Followed by some messages in german (because the SQL Servers language is german)… “Fehler bei der Anmeldung” which means: “Access Denied”

Solution:

The Service Account of the SharePoint Web Services System needs “db_owner” rights on the migrated content databases!!! (You see this account in the event log message!!!)