XPS15 9550 - Thunderbolt Controller Driver install fails

On Aug31, 2018 I was prompted by Dell Support Assist that I needed to install a new Thunderbolt driver via a notification that popped up in the bottom right corner in Windows 10. Installing stuff when prompted has worked well for the most part so I let it install its driver. I use my computer connected to a first generation Dell Thunderbolt Dock (250W), think the model is TB15, but I am not 100% sure of that. During the installation keyboard, mouse, physical network and headphones got disconnected which I accept as normal as those are connected via the dock and as far as I know is run through thunderbolt in some way. The two displays I use via the dock still worked through the installation though.

Anyway, the installation seemed to complete without errors, at least no errors was shown in the notification window. My peripherals did however not come back. I restarted the computer even though I was not prompted that was needed "just in case" there was some initialization problem, but nothing apart from the displays connected to the dock worked.

I opened up the Dell Support Assist application and there I saw that there still was an urgent Intel Thunderbolt Controller Driver update to install - version 17.4.77.400. I tried to install it from there, but after a short while it showed in the status column that it had "Failed". I have repeated this installation numerous times during the week after the initial problem occurred, but nothing has changed - it still get status "Failed" in Dell Support Assist if I do it there and the notification for a new Thunderbolt Driver pops up every time I start my computer.

I have worked with my peripherals connected to the computer instead of the dock, but today I did a little more research and thought I could try a manual installation of an earlier version of the driver just to see if I could shake it back in working order. I downloaded the latest driver version I saw in the "Older versions" list for the Intel Thunderbolt Controller Driver on the Dell support page for XPS 15 9550 - that was version 16.3.61.275,A03 which had a release date of 20 Jul 2017.

I ran that installer manually, but that also failed. In the installation window there was a link to the installation log and the thing that stood out most to me in that was the section where the "tbt81x.inf" driver install returned error code 1603. See complete log here.

 As this manual driver installation also failed I tried one more thing - manual install of the latest driver version. I downloaded the installer for Intel Thunderbolt Controller Driver v17.4.77.400 from the Dell support site and executed that. It also failed with a very similar looking log file that you can see here.

Can you provide any recommendations on how I should proceed to get my dock back in working order? I hope the solution is not to a complete reinstall/factory reset of Windows, but something that would not not cause so much collacteral damage to my current setup.

Regards,

Erik