How to fix errors like (ParallelCombine::nopar&General::stop)

[Ali rezaie]

Hi,

I sometimes see errors like

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

or even 

"General::stop: Further output of  ParallelCombine::nopar will be suppressed during this calculation"

To run some simple lines such as : 

\[Delta]\[Xi] = (Symmetrize@

    MakeTraceless[2 PD[-\[Alpha]]@\[Xi][-\[Beta]]]) // ToCanonical

I do not know why,Could you please help me to know what  the reason is?

How can I solve them? Is the result still reliable with these errors?

Thank you very much indeed

Ali

[Jose]

Hi,

I cannot reproduce these messages. Can you separate your computation in three steps (one for MakeTraceless, another for Symmetrize and a third one for ToCanonical) and let us know which of those steps is producing the errors?

In general, please send complete code that we can run to reproduce your problem. We cannot know if you had defined a metric or not, which packages you had loaded, etc.

Cheers,

Jose.