I’ve been supporting a SharePoint 2013 environment that I didn’t build recently, and was trying to deploy some Excel spreadsheets in document libraries, which were implicitly being opened in Excel Services, except that appeared to be mis-configured. The very “un-descriptive” error message generated was a modal dialog box like the following:
After a brief search, I found the answer to my problem in a fellow Australian Consultant, Daniel Brown’s Blog Post “Unable to open excel workbook with Excel Services 2013“
As Daniel points out, it all comes down to the identity under which the Excel Services Application is running, having sufficient permissions to access the underlying content database, which is revealed by trawling through the SharePoint logs, tracing the appropriate correlation ids, and finding that it is a database access issues with message such as:
Cannot open database "WSS_Content" requested by the login. The login failed. Login failed for user 'domain\user'.
I guess the thing that this continues to confirm for me is to “follow the Microsoft guidance”. We all know that SharePoint is a non-trivial product to configure, but if the person who had built this farm, had simply followed the Microsoft Configure Excel Services in SharePoint Server 2013 guidance document, none of this would have been required retrospectively. None of it is rocket science, none of it is even particularly complicated, it’s well documented, but remarkably, people still seem to ignore or choose not to look at the Microsoft guidance on these topics.
TA's Ramblings 