System.Runtime.InteropServices.COMException (0x80080005): Retrieving the COM class factory for component with CLSID

I am replacing MS Word MergeFields with data from SQL Server in a simple asp.net c# application and it works fine locally but when i publish it often i get the following:

System.Runtime.InteropServices.COMException (0x80080005): Retrieving the COM class factory for component with CLSID {00020906-0000-0000-C000-000000000046} failed due to the following error: 80080005.

I tried giving both IIS_IUSRS and NETWORK SERVICE full access, and also set the identity to interactive in the DCOM config but it didn't fix anything.

For nasty permissions stopping you from doing what you expect, (I've encountered in the past too). Sometimes I've had to change my DCOM/COM+ permissions to an object too. At the DCOM Config tab screen for your project, under security, make sure BOTH "Launch and Activation" and "Access" have been customized to explicitly include the user account you intend to allow.

Now, one more thing -- just to rule out all others. I've even gone the extent (for testing / confirmation only) is that on the "Identity" tab, you can select the "Interactive User", "Launching User" or "This User". I would put in your actual account that you KNOW has permissions (ensure your account is also in the launch and activation... and access permissions on previous tab). And also to enter/confirm your password.

If that still fails, then I would try adding the ADMIN account for permissions and try that... just for purposes of yes, its permissions based on a user. Once confirmed, you can scale it back, and even create some simplified restricted user who's primary purpose is to run this utility, and this new user has its adequate permissions to do so.

Once that is done, you should be good to go.

Now, that said, I've run into another flakey thing and its been a while, so it may not be an issue any more. Periodically, during certain "Windows" updates, the functionality would just stop working. However, if all I did was go back into user maintenance, do change password for the account (even if just keeping it the same original password) and saving it, then going back into DCOM and enter/re-confirm saving it there too, all became functional again.