Error "Throw::nocatch: Uncaught Throw[False] returned to top level" given each time I open a new Mathematica 10.1 session

Eventually, I was able to reproduce this problem. The way to fix it is to delete the MLCleaner-1.0 directory in $UserBaseDirectory/Paclets/Repository, then restart Mathematica and run RebuildPacletData[].

The underlying reason is the same as in 84539, though it was triggered by the use of a different top-level function depending on Throw/Catch during kernel startup.

I had exactly this same problem two days ago. I tried numerous fixes, but I finally had to uninstall Mathematica and all of its library files, and then I did a clear install of Mathematica. This fixed the problem, except it initially seemed to have broken my CUDA.

After the clean install I couldn't get Mathematica to automatically sign me into the Wolfram cloud, but that problem was fixed by executing CloudConnect[] in new Mathematica session.

My broken CUDA was fixed by manually downloading the Mathematica 10 CUDA resources file from the Wolfram server and then executing:

Needs["CUDALink`"]

CUDAResourcesInstall["path-to-download", Update->True]