happen/occur

- No problem occurred with the new tool.
- No problem happened with the new tool.

Q1. I think I see "occur" used more frequently in the above context. Is the second one also OK?

Q2. Is it more common to use a plural form for "problem"? (i.e., "No problems occurred...")

Thank you.

"No" and "problem" or "occured" don't seem to go well together in a sentence but "no problem occured" is the better of the two.

Instead, I would say "there were no problems with the new tools".

Correction:
"No problem" and "HAPPENED" or "occured" don't seem to go well together in a sentence but "no problem occured" is the better of the two.

Instead, I would say "there were no problems with the new tools