Excel Automation Windows Service

Question

I have a Windows Service that runs the Excel Interop in order to automate the execution of various macros. However, I am running in a peculiar issue when I try to run a macro which access a database using Windows Authentication...

If the macro is run through the Windows Service, the workbook is opened and the macro is execution is started but the application hangs (presumably at the data access portion).

If, however, the macro is run through the Visual Studio debugger, using the same implementation as the service (they call the same class library), it executes, saves the workbook, and closes as expected.

I'm sure this has something to do with impersonation, but I can't seem to figure it out. I have the windows service running under my user and I have also modified the default COM properties in the Component Services to Impersonate instead of the default Identify.

Any help would be greatly appreciated, as it would be preferred to run as a windows service and not a console application.

Answer 1

Maybe I'm a bit late, but here I go anyway:

I had a similar issue and solved it by creating a Desktop folder in C:\Windows\SysWOW64\config\systemprofile and C:\Windows\System32\config\systemprofile.

It seems that Excel is not able to run under a specific user when used in a Windows service. Therefore, it runs with the LocalSystem service account, and it requires a Desktop folder in order to interact with Excel interop.

I have no further explanation, but it worked for me and it didn't cause any other know issue. I searched quite a lot for a definitive answer, but everything I found described the solution without specifying a reason.