Did your Creation Kit suddenly stop working? [solution here]

[gargamel9]

So, I finally had time to get back to working on my mods again, but this wouldn't be Bethesda if things were as easy as resuming your work where you left off. I double-clicked the CK icon, briefly the steam splash screen appeared, and that was it. Running it from the game folder or Vortex didn't help either.
With the steam splash screen I have realized that on reinstall, I left the steam shortcut on my desktop, instead of my custom direct shortcut. Since Steam updates can only be suspended until you launch an app again from steam, this was the likely culprit. I already had downloaded the Steam file depots of the version patchable with the Unofficial Downgrade Patcher, so I just pasted the files and ran the patcher. But then things started to get serious. Even though the patch ran correctly. CK still would not launch.
So I started digging, and digging, and no search results seemed really to fit my issue, which is why I am making the post here, so others do not have go through the same pain. Took me the better half of the day, and finally I stumbled upon an old post which mentioned that failure of the CK to launch can be caused by a dll mismatch in the game directory.
So I went ahead and tried to replace the mentioned dll (steam_api64.dll) with one from Skyrim VR. And this time, I got an error window (see attached picture). Upon further search this confirmed my suspicion that this has to do with the dlls.
So, eventually, I came up with the following hypothesis. Even though updates of Skyrim were disabled, the accidentally triggered update of CK not only updated its own files, but also some of Skyrim itself. That's why the reapplication of the depot files and the patcher didn't work. So I reapplied the skyrim depot files and the patcher, and then the same for CK, and.... drumroll... it worked!
Whether you have encountered this issue or not, make sure updates are disabled for CK, and that the shortcuts point to the exe directly.
That's it. Sorry for the roundabout way of explaining this, but I just had to vent a bit
Cheers.