I have found a number of entries in the ${UVHOME}/errlog file reporting this error message:

Unable to create new process. Will try again.

I suspect it might be from executing the VOC verb SH (as in SH -c '{run unix command here}')

Though the "Will try again" portion does not fit with that as I have only ever thought of the "SH" command as a single-attempt process.

Does anyone know what actually does trigger these log entries?

Thanks

I recall this error from years ago when attempting to start PHANTOM processes. To my knowledge, the error occurs when an attempt to fork a new process fails due to an OS limitation on the number of available processes. I believe there was some retry logic which would account for the "will try again" phrase in the message. I think your example of the SH command would fit as UV does fork a new process when executing the SH command.