My mail_report: Finished execution of Mail Reports with result: Failure, Error message: is not of type String
If you run it manually from the scheduled jobs screen you need to edit the mail report entry there and set those parameters. Normally you would set them in the specific command you use for cron for a specific report.
See https://docs.civicrm.org/user/en/latest/initial-set-up/scheduled-jobs/#job_mail_report. For getting the instance id that's a good point. There's a couple ways but one is to go to Reports -&gt; All Reports and then hover over the View Results link and in the url that appears in the browser status bar it's the number after the word &quot;instance&quot;, e.g. if it says civicrm/report/instance/5?force=1&amp;reset=1 then the id is 5.