Error 500 after add a calculated field in workflow

No, sorry, that looks normal to me.

You need to focus on any messages saying “FATAL” or “ERROR”. Sometimes "WARNING"s are relevant, but not very often.

I have more hopes of finding an interesting clue in your php_errors.log (or whatever your web server log is called) than in suitecrm.log, because 500 errors is a web server crash.