Consider a scenario where you planned the migration from ISA to TMG, you read the migration guide and you watched the migration video from Jim and Mohit. You did all the homework and on the day that you try to migrate you get an error saying: Import Failed Error 0x004040f. When you click Details button you will see the message: “No CA Certificate selected for HTTPS Forward Bridging”.
What happens is that if you install TMG and right after installing you launch the Getting Start Wizard, follow all the wizard then follow Web Access Policy wizard and try to enable all the features that are in there you will ended up with configuration that is not clean. You will have rules and components already configured in TMG, which shouldn’t be there while importing the settings from ISA. So, make sure that you have a really clean install prior to import the data from ISA.
Have a good TMG Migration…
Chapter 6 of the TMG Book is your friend !!