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“OS X could not be installed on your computer”

Hello everyone,


my MacBook Pro (Retina, 13-inch, Early 2015) was slow so I have tried to do a factory reset following these steps:


https://uk.pcmag.com/macintosh-os-x/121511/how-to-factory-reset-a-mac


After erasing my data, I have tried to reinstall OS X Capitan but it comes up with “OS X could not be installed on your computer”.


I have then tried to change the date, using this video: https://m.youtube.com/watch?v=LyqBz2p8KB0


However, it hasn’t worked. It could be that I am not following the steps correctly.


Would anyone be able to explain what I should do, please?


Any help and advice will be massively appreciated as I am not any good with this as you can probably tell... Thank you in advance!





MacBook

Posted on Nov 20, 2020 4:05 PM

Reply
Question marked as Top-ranking reply

Posted on Nov 20, 2020 5:06 PM

Never reset your mac without having a copy off your operating system on a bootable USB,

Apples Recovery Servers have not been update with OS's that have valid certificates and this

is the problem you are probably having.


When you reset the date did you follow this method.


Connect your mac to your router via cable, not WiFi


Boot to your Recovery HD, click on Utilities in the menubar select Terminal.


Make sure WiFi is switched off, it can reset the date back to today.


Enter a new date, for example or just copy and paste


sudo date -u 011421002016


press Return

enter your password

press Return


If Terminal returns an error saying sudo : command not found, then try again without sudo.


Now try downloading the OS.

If this works then when the OS is installed and booted up you can Open System Preferences> Date & Time

and reset the time back to today.


Do you have access to another mac that you know is/ was capable of running El Capitan.

If so follow these instructions for downloading El Capitan and creating a bootable USB installer.


How to get old versions of macOS – Apple Support


Go to Download macOS and click on OS X El Capitan 10.11

this downloads InstallMacOSX.dmg to your Downloads folder.


The next section can only be done on a mac that is capable of running El Capitan,

a mac that came preinstalled with an OS later than El Capitan will refuse to do the next bit.


When downloaded open to InstallMacOSX.pkg, double-click on

that and an installation window will open, this does not install El Capitan

but converts the InstallMacOSX.pkg to the Install OS X El Capitan.app which 

you will find in your Applications folder, it should be 6.2GBs in size.


 (If the installation window asks which disk you want to install to, you must pick 

the disk that you are booted to at the time. Not any internal or external disk that 

you want to eventually install El Capitan on, that is for later.)


To start the installation of El Capitan double click on the Install OS X El Capitan.app.


Create a bootable USB installer disk using the Install OS X El Capitan.app in the Applications

folder and the createinstallmedia command in the Terminal app. 


Read the instructions here,

How to create a bootable installer for macOS – Apple Support


Having made the bootable USB installer you're ready to erase and then install a fresh copy of El Capitan.


The USB should be plugged directly to your mac. 

Restart the mac while pressing and holding the option/ alt key.

In minute or two you will see the Startup Manager, select the USB and press Return.


When booted to the USB you will see a Utilities panel, select Disk Utility and press Return.

In the left hand panel highlight the Disk not the indented Volume, click Erase.

Give the Disk a name.

Format: Mac OS Extended (Journaled)

Scheme: GUID Partition Map

Click Erase.

When Done Quit Disk Utility.


Click on Install OS X press Continue the installation process should start up

follow the prompts.


If you get your mac back running through the Recovery Servers download El Capitan as described above

and make a bootable USB installer and keep it safe and use that for any time you want to reset your

mac and reinstall the OS. This is easier and quicker than using the Apple Recovery Servers.

Similar questions

2 replies
Question marked as Top-ranking reply

Nov 20, 2020 5:06 PM in response to GiadaR_

Never reset your mac without having a copy off your operating system on a bootable USB,

Apples Recovery Servers have not been update with OS's that have valid certificates and this

is the problem you are probably having.


When you reset the date did you follow this method.


Connect your mac to your router via cable, not WiFi


Boot to your Recovery HD, click on Utilities in the menubar select Terminal.


Make sure WiFi is switched off, it can reset the date back to today.


Enter a new date, for example or just copy and paste


sudo date -u 011421002016


press Return

enter your password

press Return


If Terminal returns an error saying sudo : command not found, then try again without sudo.


Now try downloading the OS.

If this works then when the OS is installed and booted up you can Open System Preferences> Date & Time

and reset the time back to today.


Do you have access to another mac that you know is/ was capable of running El Capitan.

If so follow these instructions for downloading El Capitan and creating a bootable USB installer.


How to get old versions of macOS – Apple Support


Go to Download macOS and click on OS X El Capitan 10.11

this downloads InstallMacOSX.dmg to your Downloads folder.


The next section can only be done on a mac that is capable of running El Capitan,

a mac that came preinstalled with an OS later than El Capitan will refuse to do the next bit.


When downloaded open to InstallMacOSX.pkg, double-click on

that and an installation window will open, this does not install El Capitan

but converts the InstallMacOSX.pkg to the Install OS X El Capitan.app which 

you will find in your Applications folder, it should be 6.2GBs in size.


 (If the installation window asks which disk you want to install to, you must pick 

the disk that you are booted to at the time. Not any internal or external disk that 

you want to eventually install El Capitan on, that is for later.)


To start the installation of El Capitan double click on the Install OS X El Capitan.app.


Create a bootable USB installer disk using the Install OS X El Capitan.app in the Applications

folder and the createinstallmedia command in the Terminal app. 


Read the instructions here,

How to create a bootable installer for macOS – Apple Support


Having made the bootable USB installer you're ready to erase and then install a fresh copy of El Capitan.


The USB should be plugged directly to your mac. 

Restart the mac while pressing and holding the option/ alt key.

In minute or two you will see the Startup Manager, select the USB and press Return.


When booted to the USB you will see a Utilities panel, select Disk Utility and press Return.

In the left hand panel highlight the Disk not the indented Volume, click Erase.

Give the Disk a name.

Format: Mac OS Extended (Journaled)

Scheme: GUID Partition Map

Click Erase.

When Done Quit Disk Utility.


Click on Install OS X press Continue the installation process should start up

follow the prompts.


If you get your mac back running through the Recovery Servers download El Capitan as described above

and make a bootable USB installer and keep it safe and use that for any time you want to reset your

mac and reinstall the OS. This is easier and quicker than using the Apple Recovery Servers.

“OS X could not be installed on your computer”

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