# ParallelTable::nopar: No parallel kernels available; proceeding with sequential evaluation

I am trying to use a the following code:

Total@ParallelTable[If[RegionMember[vuoto, {elettrone[[n, 1]], elettrone[[n, 2]], elettrone[[n, 3]]}],1, 0], {n, Length@elettrone}]


to calculate the number of electrons that escape from a surface. Everytime I run this code I get the error:

ParallelTable::nopar: No parallel kernels available; proceeding with sequential evaluation.

In Evaluation -> Parallel Kernels Configurations... I have the following settings:

so it seems that Mma knows I have 4 cores, but won't start parallel kernels.

How do I solve this problem?

I use version 11.3 for Windows.

• Did you try restarting the kernel? If that didn't help, did you try an explicit LaunchKernels? If that didn't help, did you try restarting your computer? – Szabolcs Sep 26 '18 at 10:51
• @mattaiv27 And if nothing helps: Try to perform a clean reinstall of Mathematica. You got also some other weird things going on in your copy of the software, if I recall correctly. – Henrik Schumacher Sep 26 '18 at 11:18
• @Szabolcs rebooting the computer did the trick; thanks. – mattiav27 Sep 27 '18 at 7:19
• It is possible that some of your old parallel kernels got "stuck" (didn't exit properly) and used up all available licenses. However, in that case, I would have expected an error message specifically mentioning the license. Rebooting is a surefire way to get rid of any stuck kernels. – Szabolcs Sep 27 '18 at 7:25