In my attempt to move from SQL Server 2000 to 2005, I backed up and restore both our DNN and portal databases to 2005.  I also created a website exactly like the portal one, except that it points to the new DNN folder with updated connection string.

When I go to the test portal, the login screen looks fine.  However, after I login I get the following error on a blank page:

An error has occurred writing to the exception log. The permissions are not set properly on the log file or directory, or the log file has been marked as READ-ONLY.

All permissions for databases, websites, folders are the exact same.  After I get this message, I click reload to reload the page and I get the same error.  If I click the back button, I see the page I originally intended to see and all my tabs and see that I'm logged in.  And I can also access my data.  I have looked pretty hard on google and haven't found much useful info on the above error message.

Any suggestions?

This seems like a database error ... so I'd look there.

Make sure that your database user has dbo privileges. There may be other privileges required ...

I found the answer:

Permissions on the directory that DNN is installed are not correct. You must be certain that the ASPNET(Win2k, WinXP) or Network Service (Win2k3) has modify permissions.