Problem Booting Windows 10 from external ssd with Boot Runner 3.1


I’m struggling to get BootRunner to boot my external Windows 10 installation, I can bless the volume via terminal [sudo bless /usr/sbin/bless -device /dev/disk3s1 -setBoot -nextonly] and it works fine.

I’ve set SIP to csrutil enable --without nvram
I’ve tried all 3 options in the force boot type, EFI, Legacy & Volume EFI
I’ve also uninstalled and reinstalled BootRunner, still no joy.

No matter what I do it just doesn’t seem to want to work

Running 10.14.1 and Boot Runner 3.1 if that combination has any bearing on the solution.

I’d be grateful for some advice on what to try next

it could be that the external drive is getting unmounted at the login window. From the user guide at :

  1. OS X will unmount any volumes contained on removable drives when the user logs out, and will also unmount them if the removable drives are plugged when the Login Window appears. In order to see external drives at the Login Window, run the following defaults command:

sudo defaults write /Library/Preferences/SystemConfiguration/autodiskmount AutomountDisksWithoutUserLogin -bool true


Thanks for response, I had already set this value and can confirm the volumes stay mounted after logout as they are shown on the Boot Runner screen.

What exactly happens in the background when I select the drive I’d like to boot from, does this use bless setboot?
Are there any options to configure the parameters set, as I say when I run this command from terminal [sudo bless /usr/sbin/bless -device /dev/disk3s1 -setBoot -nextonly] it happily boots.

What and where can I look for in the logs to give me some idea what’s failing?

I do have an issue where the external drive doesn’t mount from a clean restart, I have to login before it mounts which I think is to be expected and it stays mounted okay after logout.
I think I’ll have to look at a putting something to mount this at /Library/LaunchAgents/ level but I need to resolve the issue of it not booting first.

Yes, boot runner runs that command. You can verify the exact command by looking in the log as it prints out the command when it is run:

Logging Options

Boot Runner logs messages via the Apple System Logger. To view the logs, open Terminal and enter in the following command:

log show --style syslog --predicate 'process contains[cd] "Boot Runner"' --info --last 2d

You can adjust the “2d” for a longer or shorter time period. You can specify a number and then m (minutes) h(hours) or d (days). For example: “–last 2m” or “–last 3h”.

To send the output to a file, redirect the output:

log show --style syslog --predicate 'process contains[cd] "Boot Runner"' --info --last 2d > ~/Desktop/bootrunner.log

This will save the last 2 days of Boot Runner output to a file on the current user’s desktop called “bootrunner.log”.