Disk Utility Error 254 **SOLVED**

This persistent problem has been a bugaboo for years and has been the cause of many long nights and huge frustration for me. You follow the standard instructions for putting an .iso on a USB using Restore in Disk Utility and it doesn't do it, returns an error 254.

Here's the workaround that worked for me, once I noticed the problem ISOs had no embedded partition information:

1) CONVERT the problem ISO to DMG in Disk Utility
2) DOWNLOAD "DMG Converter" (freeware) from the web.
3) Set convert tab, file format to ISO (JOLIET)/UDF HYBRID IMAGE.
4) Allow to run and finish. This seems to restore
5) Now use Disk Utility to Restore the new ISO to your USB drive.

Good luck.