We have a strange issue that seems to appear after the weekend. It appears that when opening documents from our SharePoint 2010 environment (Excel, Word, etc) the end user no longer is able to 'check out' or 'check in' the document from the client application. Instead, they receive a notice at the top of the application:
Server Read-Only This workbook was opened from a server is read-only mode.
..and the option is there to "Edit Workbook".
When clicking this option, they receive an error:
"A problem occurred while connecting to the server. If the problem continues, contact your administrator."
Now, I have diagnosed the following things:
Checking out the document first from the browser and then editing it allows the client to continue working, but they must checkin/checkout from the browser - there is no option in the client application anymore
Ensured that Windows 2008 WEBDAV is disabled on the Web Front Ends and the Application server. This has always been disabled as far as I know. An article I read mentioned that the Windows 2008 WEBDAV will interfere with SP2010 's WEBDAV and it should remain disabled.
Turned on Fiddler and didn't notice any errors whatsoever. Just a call to "/_vit_bin/cellstorage.svc/CellStorageServer" when the "Edit Workbook" button is clicked from within the client application.
Verified I have Version 14 of the "OpenDocuments" class IE add-on, which corresponds to our Office 2010 version.
I am currently at a loss as to what may be causing this all of a sudden. Something obviously changed on the weekend, but I cannot seem to determine WHAT exactly. Thoughts?