VML error msg- Training process was terminated unexpectedly

Hello,

Can anyone of you advise why I'm getting an error message which says "Training process was terminated unexpectedly?"

I've fulfilled the minimum document requirement of 50 each per training, and each document is less than 30 MB

Does the document need to be in a specific format? CSV, word, notepad?

Can we use VML for message.eml?

Pls help

Thank you !!