WIM Image Restore to External SSD

Hi Tim,

Thought I’d surface this topic from our previous thread.
I’v been unsuccessful at moving my Bootcamp partition to an external SSD (Samsung T7).

To recap:

  • New iMac running Catalina 10.15.7
  • Bootcamp installed successfully on internal Bootcamp partition
  • I used Winclone’s WIM mode to create an image of the working Bootcamp partition
  • I restored the image to a Samsung T7 SSD, freshly formatted as GUID, 1 partition, exFat
  • Restoration completed successfully
  • SIP is off and external boot devices are allowed
  • When I boot from the Samsung T7, it shows the 4 pane “window” with a wait circle, then reboots to macOS after a bit.
  • Booting into Safe Mode gave me an sihost.exe error dialog: sihost.exe - System Warning, Unknown-Hard Error with an OK button. Clicking OK gave me a black screen with a mouse pointer and a flashing wait circle. I waited 10+ minute then rebooted.

Any ideas?

Two additional questions I’m hoping someone can answer:

  • Is there a secret to getting into safe mode while booting? I tried F8 and F5 without success.
  • Is there a way to choose an external boot device as the default startup device in macOS? I am not presented with the external drive from the startup disk panel in system preferences, despite the drive being attached, mounted and visible in Finder.