C# console app that does Excel Interop - failing when running as scheduled Task -System.UnauthorizedAccessException

Question

As the title states, I have a C# console app which uses interop to open Excel and create a new workbook. The code works fine when running the console app via command line. However this exception is thrown when running the console app via a scheduled task:

System.UnauthorizedAccessException: Retrieving the COM class factory for component   with CLSID {00024500-0000-0000-C000-000000000046} failed due to the following error: 80070005

It is thrown from the following call:

_xlApp = new Excel.Application()

The scheduled task is setup to use my credentials (I am an administrator). Based on other forums I have made sure I have granted full control to my account at Component Services --> Computers --> My Computer --> DCom Config --> Microsoft Excel Application, but no luck.

I'm on Windows 7 Enterprise 64 bit. Not sure what the next step should be, any help is appreciated

Answer 1

The error 80070005 is a COM Access Denied error. Are you sure that your credentials have the ability to instantiate the Interop Library? Check this link and follow some of the debug steps.
(I know you said you did the DCOMConfig thing already, but there are more test scenarios in this link and hopefully something here will help you)

Answer 2

I ended up writing a windows service to call out to a library containing the Excel generation code. That fixed the error. However there was another COM exception when calling the workbook.Save() method. No matter what I tried that error would not go away. I read another post which stated that this was a security precaution and therefore by design.

However, calling workbook.SaveAs() will produce the same result and works fine when called from a windows service.

Thanks for the input funkymushroom. Hopefully this post will be helpful to someone else struggling with Excel Interop automation.

Answer 3

I had the similar issue, I have resolved the issue by performing the following steps.

DCOM Configuration

1. Click Start -> Run
2. Enter DCOMCNFG and press OK. This will open the DCOMCNFG window.
3. Browse down the tree to Console Root -> Component Services -> Computers -> My Computer
4. right-click on "My Computer" and select properties
5. Select the "Default Properties" tab
   • Enable Distributed COM on this computer - Option is checked
   • Default Authentication Level - Set to Connect
   • Default Impersonation Level - Set to Identify
6. Select the "COM Security" tab
7. Click on Access Permissions ' Edit Default a. Add "Anonymous", "Everyone", "Interactive", "Network", "System" with Local and Remote access permissions set.
8. Click on Launch and Activation Permissions ' Edit Default a. Add "Anonymous", "Everyone", "Interactive", "Network", "System" with Local and Remote access permissions set.
9. Click on OK
10. Close the DCOMCNFG window

Later I got an exception while opening the Excel. So please make sure that the following paths are available on the server.

• C:\Windows\SysWOW64\config\systemprofile\Desktop
• C:\Windows\SysWOW64\config\systemprofile\AppData\Roaming\Microsoft
• C:\Windows\SysWOW64\config\systemprofile\AppData\Local\Microsoft

This might help guys like me.

Answer 4

I also had this problem - it turned out that on the scheduled task I needed to tick the box "Run with highest privileges" on the General tab of the task set-up. This resolved the problem - it was so simple! Hope it helps someone else too.