Free Test Drive Unlimited 2 DLC release proves problematic

The launch of Test Drive Unlimited 2 was less than smooth, resulting in multiple user complaints and the promise of some free DLC as an apology.
That DLC has now been released, and full details of the additions, bug fixes and changes can be read on the game’s official site. The “Exploration Pack” supposedly adds 20 new missions, a couple of new mission types, the ability to sell reward cars and a bunch of other automobile-related stuff.

Unfortunately, the cheeky hand of irony has chosen to slap this sorry-for-the-launch-being-buggy DLC release in the face, resulting in a series of PC installation errors. There are two separate threads on the Test Drive Unlimited 2 forums dealing with these problems, and delivering possible workaround solutions.
One proposal is to “delete the UpLauncher.localdb file from your TDU2 instalation folder,” although several replies to the thread suggest this doesn’t actually solve anything for them.