System.Unauthorized Access Exception: Retrieving the COM class factory for component with CLSID failed

Symptom

After opening a workflow job through the web browser you may get the following exception page.

System.UnauthorizedAccessException: Retrieving the COM class factory for component with 
CLSID {B5DF154A-A87D-4858-8B32-9F60B3E62B65} failed due to the following error: 80070005

Cause

The account that the web site application pool runs under does not have sufficient permissions to call onto Workflow agent component.

Resolution

Give the account that the web site application pool runs under DCOM permission on the Workflow agent component:

1. Start -> Run and type dcomcnfg to open Component Services.
2. Under the Computers folder expand the DCOM config branch and locate the iwwfea component.
3. For the ‘iwwfea’ component give ‘Local Launch’, ‘Local Activation’ and ‘Local Access’ permissions to the account that the Web site application pool runs under