MacBook Pro mid 2009 won’t boot from external usb

It would have helped if you had posted a clear picture instead of a picture with an extremely dirty screen that is hard to see. Plus you have not provided enough details to explain what we are seeing in the picture and you seem to be doing things in an extremely difficult way by trying to access a Time Machine backup. Assuming you can access the full installer app from the TM backup like shown in your picture, then it would be so much easier if you actually transferred that file to another drive to make the path much easier especially when posting on these forums.

From what little I can make out, you need to add the "--applicationpath <path-to-installer-app>" which is clearly mentioned in the error message in your picture. Your USB stick also needs to be erased as GUID partition and MacOS Extended (Journaled).

I really don't know what you know or don't know, but you posted a gray screen with NOTHING on it.

A response describing what is supposed to happen with a properly created and working USB-stick installer is not out-of-line, and not talking down to you. it is just providing information addressing what is seen and not seen on the screen you posted.

You have included a later picture showing a portion of a Disk Utility screen. That screen appears to show an APFS Volume. APFS Volumes were first created for the boot drive only in 10.13 High Sierra, and are not seen as valid drives for installation on any MacOS older than 10.13. I don't know if that is even involved, or how it applies.

When you hold the Al/Option key at startup, the Mac will look around and develop a list of drives that APPEAR to be bootable.

If your USB thumb drive appears as an Icon and can be selected, it had the right disk structure and at least one of the required files in the right place.

As it boots up, the solid Apple should appear. This is loaded with the first "blob" of software from a known location on the drive. Then the progress bar should appear as it attempts to Mount the drive and proceed.

jamesrgraber wrote:

internal drive unknown atm.

i just pulled from storage as previous owner declared it ‘dead’ and bought a macbook air 128 which she barely uses as she is always getting the low on storage message and won’t listen for spit.

anyway now i’m looking to flip it and i’m at a brick wall just booting from an El Cap boot USB.

im going to try snow leopard while i'm waiting on an answer here going from educated guess that it's minus an EFI or boot rom update or such or two before it can be on el cap

as one can see boot usb swell

What is atm...?

What is " won’t listen for spit..." ?

What is " one can see boot usb swell" ...?

MacBook Pro mid 2009 won’t boot from external usb

How to create a bootable installer for macOS - Apple Support

if you have 10.6.8 installed, be sure to run ALL the available software updates. When you are done, the Mac App Store icon will be available, indicating you could use that to make progress. (But it is a bit more complex than that for El Capitan and later.)

The oldest possible browser that can do encryption could be installed separately under MacOS 10.9 Mavericks. But you are right to be pursuing 10.11 El Capitan. 10.11 is a notable waypoint, required if your Mac could run more modern MacOS versions (which this 2009 model can not).

Tricks for making the creation of the USB stick simpler:

Start by naming your USB stick exactly MyVolume. Then no error-prone editing of the Terminal command is required.

The command in the article sprawls beyond the margins of the document. You must take pains to collect the ENTIRE command and paste it, unmodified, to the command-line.