sp_Blitz error: "File '' either does not exist.."
There's a weird bug that only pops up on some instances of SQL Server when the Trace File path has problems. I can't diagnose those, but we took some steps to avoid that bug which are in the latest version of sp_Blitz.

Please head over to firstresponderkit.org to grab the newest version, and file an issue at the GitHub repo if you run into anything else.

Thanks!