Level 1 (4 points)

iMac (2009) fails to install El Capitan after reset

Hello all,

I was hoping for a little assistance with a recent problem I've been having regarding the installation of software after a system reboot.

I recently reset an old iMac, because my Dad recently passed away and I wanted to clear any of his saved details before giving the computer to my neighbour son.

Whilst it's an older machine, it was working perfectly prior to me doing the reset.

But sadly, now having done the reset, the software (El Capitan) doesn't seem to want to re-install.

The errors that display are...

"The server gave an error during download: 403 Forbidden" and "An unexpected error occurred while signing in: plist parsing error".

El Capitan is the most up-to-date software I'm able to install on this Mac. Additionally, I also tried to install the original software which came with the iMac (Snow Leopard) as I have it on a disk, but sadly it seems like the disk can't be read.

I would love to know if anyone has any ideas on how I can solve this issue. Whilst I'm no longer using the machine, I had already promised it to my neighbour's child, so I would love to get it working again if possible.

I did have a conversation with the Mac team and they suggested I posted in here, as there are more legacy users in the forums than there are on their current support team. She suggested that someone might be able to advise on how to create a bootable installer—but I'm also open to other ideas if there are other potential solutions.

Any help or advice would be hugely appreciated.

iMac Info: The Mac is a 2009 iMac (which originally came with the Snow Leopard operating system) and the most up-to-date software it can run is OS X El Capitan.

Many thanks,

Greg

Posted on Oct 25, 2026 9:29 AM

5 replies

xDJZak

Level 1 (60 points)

Nov 8, 2026 4:36 PM in response to Gregy901

You will need a USB flash drive and a copy of El Capitan you downloaded on another El Capitan-supported Mac from this link: https://support.apple.com/en-gb/102662

Then create a bootable installer from this link: https://support.apple.com/en-gb/101578

This is because El Capitan recovery no longer works.

HWTech

Level 9 (78,350 points)

Nov 10, 2026 7:27 AM in response to claus237

claus237 wrote:

I normally, recommend, LINUX, for that type, of vintage iMac!

But if a USB-Bootable with MacOS El Capitan, can do the job, that´s even better?

Recycling, is an option, when everything else had been tried?

But that's just my opinion!

If Apple had a better wider more generalized method of creating a bootable macOS USB installer, then yes....reinstalling macOS using a USB installer is best. Unfortunately the only Macs which can create the bootable El Capitan USB installer are models 2007 to 2015 generally.

Installing Linux on this iMac is actually a very good idea especially considering the age of this iMac and the severe limitations of macOS El Capitan. Linux would give the person a computer running a current OS which also has access to all of the popular third party web browsers (Firefox, Vivaldi, Brave, Google Chrome). Plus Linux has access to lots of free open source software which can allow someone to learn just about anything. LibreOffice is included as an office suite similar to MS Office.

Linux also runs well on older systems which have more limited system resources. My only concern for such an old iMac is whether the internal Hard Drive is still healthy and whether it has at least 4GB+ of memory.

If going with Linux, I would recommend starting with Linux Mint because it is relatively easy to use and seems to just work on many Macs. Linux is not for everyone, but it is a good way to extend the useful life of older computers. Linux does require that the person learn a new OS.

den.thed

Level 10 (99,154 points)

Oct 25, 2026 10:50 AM in response to Gregy901

While giving that iMac to someone seems like a noble idea. It is actually a very bad idea because it can not safely be used on the internet and is to old to download games or app's from the Mac App store.

My recommendation is to recycle it at your local Apple Store or E-Waste Recycler. Then apologize or say that it's dead if you have promised it to the neighbors son.

claus237

Level 2 (256 points)

Nov 9, 2026 2:36 PM in response to xDJZak

I normally, recommend, LINUX, for that type, of vintage iMac!

But if a USB-Bootable with MacOS El Capitan, can do the job, that´s even better?

Recycling, is an option, when everything else had been tried?

But that's just my opinion!

HWTech

Level 9 (78,350 points)

Nov 10, 2026 7:15 AM in response to xDJZak

xDJZak wrote:

You will need a USB flash drive and a copy of El Capitan you downloaded on another El Capitan-supported Mac from this link: https://support.apple.com/en-gb/102662

Then create a bootable installer from this link: https://support.apple.com/en-gb/101578

This is because El Capitan recovery no longer works.

Excellent advice. Just to clarify that Macs which can support macOS 10.11 El Capitan are generally models 2007 to 2015. That is a generalization sometimes with a couple of exceptions, so you can confirm whether a specific model is compatible by using the information in the following article:

https://eshop.macsales.com/guides/Mac_OS_X_Compatibility

Originally posted at discussions.apple.com/thread/256382734