caret train method not working (something is wrong for all accuracy results) for outcomes with >2 categories

Question

Hi I know someone asked similar issues before but no clear answer yet (or I tried their solution without success: Caret error using GBM, but not without caret Caret train method

Answer 1

I had allowParallel = TRUE in the train function and the machine I was working on did not have multiple cores. After I commented that statement, I did not get the error.