Bootable USB Sierra not working

The following is the procedure I use and illustrates what you should see. Perhaps you will notice something different than what you have been experiencing.

To create a standalone installer on a USB flash drive or similar removable media, refer to the following instructions: Create a bootable installer for macOS - Apple Support.

Expanded instructions are as follows:

• Format the USB installer as Mac OS Extended (Journaled) and GUID Partition Map.
• Make sure its icon is present on your Desktop. Its name isn't important because createinstallmedia will change it.
• Also, the Install macOS Sierra app must be present in your Mac's Applications folder, otherwise the pathname won't be correct.
• Make the Finder's Applications window small enough so that you can see it, the Terminal window, and the USB drive icon, all at the same time.

Select the following line by dragging your cursor from just prior to the word sudo to past the word volume:

sudo /Applications/Install\ macOS\ Sierra.app/Contents/Resources/createinstallmedia --volume

Then, Edit > Copy.

Go to the Terminal window, paste that line into the Terminal window, and type a space character. Stop right there; do not press Return.

Drag the USB flash drive icon from your Desktop to the Terminal window, and stop again.

Then, type (or copy/paste) the following into Terminal:

--applicationpath

... followed by another space character.

Then, drag the Install macOS Sierra icon from your Applications folder into the Terminal window.

Finally, you can press Return.

This is an example of what should happen. The name of the USB drive is "untitled" in the following:

MacBookAir2:/ john$ sudo /Applications/Install\ macOS\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/untitled --applicationpath /Applications/Install\ macOS\ Sierra.app

Password: (type your Admin password - it will not be echoed, not even with •••• characters. Then press Return)

Ready to start.

To continue we need to erase the disk at /Volumes/untitled.

If you wish to continue type (Y) then press return: Y

Erasing Disk: 0%... 10%... 20%... 30%...100%...

Copying installer files to disk...

Copy complete.

Making disk bootable...

Copying boot files...

Copy complete.

Done.

MacBookAir2:/john$

When it's finished the name of your USB installer will be Install macOS Sierra and it will be selectable as a bootable device in Startup Manager: How to choose a startup disk on your Mac - Apple Support.

I created a boot disk exactly like John Galt explained. But when starting from the usb drive (holding down option when booting), I only see a no-entry sign. I checked that the USB drive is GUID and that the file system (only one partition) is mac os extended journaled. The usb drive is a new "Transcend USB3.1/USB-C 32 GB" connected to the USB-C port of the macbook pro 15" (mid-2017). I can mount the drive and start the installer program within the running system. But not boot from the drive to run the installer.

The system came with Sierra and is still running Sierra, I just want to create a recovery media just in case I need to downgrade from High Sierra later on. Since I could not download the image from the app store, I had to copy if from another Macbook Air.

Why is it not working?

You can make a bootable USB stick to install using this free program which will do all the work for you.

Bootable USB Flash Drive – Diskmaker X

ozbuck wrote:

I have tried several times to create a bootable Sierra USB drive, but get the same result every time. It boots up and opens the disk utility. From there any attempts to get the OS working is futile.

FWIW, I assume you understand a bootable installer can't actually run Sierra. It's meant to install Sierra on other Macs.

Struggling with the same issue.

I followed these guidelines but nothing happened after entering the password.

Just went straight to the MacBookAir2:/john$ equivalent.