How to resolve issues loading OCCI where “Microsoft.Office.Interop.Application” appears in the event log

One of our premier field engineers, David Craig, recently helped a customer troubleshoot why OCCI was failing to load after installation. For Excel, they were seeing this error in the Event Viewer:

Microsoft.VisualStudio.Tools.Applications.Runtime.CannotCreateCustomizationDomainException: Customization could not be loaded because the application domain could not be created. ---> System.IO.FileNotFoundException: Could not load file or assembly 'Microsoft.Office.Interop.Excel, Version=12.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c' or one of its dependencies. The system cannot find the file specified.

In the above error in the event log, the bold text varies depending on whether OCCI fails to load for Excel, Word, or PowerPoint.

• For Excel, the error shows Microsoft.Office.Interop.Excel
• For Word, the error shows Microsoft.Office.Interop.Word
• And for PowerPoint, the error shows Microsoft.Office.Interop.PowerPoint

David and his customer solved the issue by installing these two downloads: 

• Microsoft Visual Studio Tools (VSTO) for the Microsoft Office system (version 3.0 Runtime)
• 2007 Microsoft Office System Update: Redistributable Primary Interop Assemblies

After these two downloads were installed, OCCI ran like a champ. We are researching the root cause of this issue and will provide updates as appropriate. We wanted to get the word out ASAP so that you can quickly move past this issue if you happen to encounter it.

Having problems loading OCCI but are not seeing these errors in your event log? See our earlier post on troubleshooting OCCI errors for more tips.