For years Cadence has given me warnings, stopping work:
Canceling function, exceeds nestability limit of #.

I usually bump up the # in Options menu, but I'd really like to get a fundamental understanding of what the issue is.

~Wave

what's an "active" command?

You need to remember to hit "escape" after commands which are nested, if they're still waiting for input.

A problem I used to see happen (I've not checked whether it is still an issue) is if you have nested commands and then close the window waiting for a prompt - it remains nested, but you no longer have a means of exiting the nested command - and this eats up the nestability stack. If that's still happening (don't have time to test it right now), please report it to Cadence customer support.

Best Regards,

Andrew.