How do I create El Capitan installer on a Catalina (or post-El Capitan) installed Mac for use on USB boot installer?

Question

I have downloaded the El Capitan DMG file (InstallMacOSX.dmg) provided by Apple. The expanded DMG image contains the package "InstallMacOSX.pkg" which should be run to create the El Capitan installer but fails with the following message: This version of OS X 10.11 cannot be installed on this computer. (from the OS X Installer) That happens presumably because, quite reasonably, it would not make sense to install on top of a later version of the OS. However, in this case, I want to create a boot USB drive for an installation on another Mac.

I am stuck in a chicken and egg situation where I need another machine running El Capitan or earlier to create an El Capitan boot installer.

Answer 1

This answer was last tested 5/20/20023 using macOS Ventura on a 2018 Intel Mac mini. The USB flash drive was successfully used to do a clean install of OS X El Capitan on a 2007 iMac.

Note: On 1/31/2021, M. Justin reported this answer works for Yosemite.

Further testing has found this answer works for Sierra. In the case of Yosemite and Sierra, you will need to make the appropriate substitutions in the instructions given below. If you want a version where the substitutions have already been made, the see here for Yosemite and here for Sierra.

---

I have posted two alternative answers to this question.

• The first alternative answer involves using a virtual machine. This answer is must less of a complex, because Apple explicitly inserted code into the El Capitan installer to bypass the checking of the model when executed in a "VMware Fusion Player" virtual machine. So, Apple evidently intends for users of newer model Intel Macs to use this new answer to retrieve the Install OS X El Capitan application. Still, I would like know from Apple why they thought such a complex procedure is necessary.

• The second alternative answer involves using an older Mac capable of running Snow Leopard (OS X 10.6).

---

Below is my original answer.

Note: This answer was adapted from Klanomath's answer to a slightly different question.

Note: A version of this answer, which uses a Windows to create the USB flash drive OS X El Capitan installer, can be found here.

There is a link on the Apple website "How to download macOS" that will download a file that can be used to create the Install OS X El Capitan application. However, if the model Mac is too new to allow the installation for El Capitan, then message given below will occur when trying to create the Install OS X El Capitan application.

This version of OS X 10.11 cannot be installed on this computer.

If you are trying to create a USB installation flash drive of use on another Mac computer, then you can still use the downloaded file to create this installer. The instructions are given below.

This method was verified by using the following configurations.

• Catalina on a MacBook Pro 2017 touchbar for use on iMac 2009 24”.
• Mojave on a Mac mini 2018 for use in a VirtualBox virtual machine on a iMac 2013 21.5".
• Catalina on a iMac 2013 21.5" for use in a VirtualBox virtual machine on the same Mac.

Create Bootable Installer Directly from Downloaded File

The following steps can be used to create a USB installer for El Capitan.

1. If you have not already downloaded then InstallMacOSX.dmg file for El Capitan, then use instructions on the Apple website "How to download macOS" to download this file.

2. Use the Disk Utility to erase a 16 GB or larger flash drive. If the Disk Utility window has a View pulldown menu, make sure Show All Devices is selected. Highlight the flash drive, then click on the Erase button. Use the setting shown in the image below.

   

   Next, click on the Erase button. When finished erasing, click on the Done button.

3. Use the Finder applicaition to open InstallMacOSX.dmg.

4. Enter the commands given below. A folder named El Capitan will be created in the /tmp folder to hold temporary files.

   Note: The easiest way to enter the commands is to copy from this document and paste in the Terminal window.

   rm -rf /tmp/El\ Capitan
   pkgutil --expand /Volumes/Install\ OS\ X/InstallMacOSX.pkg /tmp/El\ Capitan
   diskutil eject Install\ OS\ X
   cd /tmp/El\ Capitan
   hdiutil attach InstallMacOSX.pkg/InstallESD.dmg  -noverify -nobrowse -mountpoint /Volumes/esd
   sudo asr restore -source /Volumes/esd/BaseSystem.dmg -target /Volumes/MyVolume -noprompt -noverify -erase
   

    
   After entering the last command given above, you may get a message similar to the one given below.

   asr: Couldn't personalize volume /Volumes/OS X Base System
   

    
   Some versions of macOS will produce this message while other versions do not. I suspect this is an fatal message because an exit status of 1 was returned.

   Inspection has determined that the part of the command that failed is unimportant.

   Therefore, I was able to ignore this error. However, the error can also be avoided by applying the following steps given in the section below titled Alternative to Using the asr Command.

5. To finish creating the bootable USB flash drive El Capitan installer, enter the commands given below.

   diskutil rename OS\ X\ Base\ System Install\ El\ Capitan
   rm /Volumes/Install\ El\ Capitan/System/Installation/Packages
   cp -rp /Volumes/esd/Packages /Volumes/Install\ El\ Capitan/System/Installation
   cp -rp /Volumes/esd/BaseSystem.chunklist /Volumes/Install\ El\ Capitan/
   cp -rp /Volumes/esd/BaseSystem.dmg /Volumes/Install\ El\ Capitan/
   hdiutil detach /Volumes/esd
   sudo bless --folder /Volumes/Install\ El\ Capitan/System/Library/CoreServices --label Install\ El\ Capitan
   cp /Volumes/Install\ El\ Capitan/Install\ OS\ X\ El\ Capitan.app/Contents/Resources/InstallAssistant.icns /Volumes/Install\ El\ Capitan/.VolumeIcon.icns
   cd "$HOME"
   rm -r /tmp/El\ Capitan
   diskutil eject Install\ El\ Capitan
   

6. Remove the flash drive. You are done.

---

Alternative to Using the asr Command

The command given below may generate a error message and/or hang depending on the version of macOS and perhaps the model Mac you are using.

sudo asr restore -source /Volumes/esd/BaseSystem.dmg -target /Volumes/MyVolume -noprompt -noverify -erase

You can avoid entering the above command by following the steps given below.

1. If the volume on the USB flash drive is no longer labeled MyVolume, then use the Disk Utility to erase the flash drive. Highlight the flash drive, then click on the Erase button. Use the setting shown in the image below.

   

   Next, click on the Erase button. When finished erasing, click on the Done button.

2. Enter the following command to create a sparse flash drive image.

   hdiutil create -type SPARSE -size 10g -layout MBRSPUD -fs HFS+J -volname MyImage -attach /tmp/El\ Capitan/MyImage
   

    

3. Basically, you want to restore to volume MyImage from the hidden file BaseSystem.dmg. The hidden file BaseSystem.dmg is shown in the Finder window image shown below. The drive OS X Install ESD can be found in the hidden volume Volumes in the root folder.

   There are various ways to view hidden files. These ways depend on the version of OS X or macOS you are using. You may have to search the web for a way that works for you.

   

   Highlight the MyImage volume shown in the Disk Utility main window. Click on the Restore button, then the Image button. Select the BaseSystem.dmg file, as shown below. Next, click on the Restore button.

   

   After a successful restore, you should see the image shown below. You can click on the Done button and quit the Disk Utility.

   

   Also, you should get the following popup.

   

4. Enter the following commands to clone to the flash drive.

   Note: The dd command takes a long time to complete. See this answer to track the progress of the dd command. The bytes to be transferred is approximately 10 GB.

   getdsk() { local "x=$(diskutil info "$2" | grep Part\ of\ Whole)"; eval $1'="/dev/r${x##* }"'; }
   getdsk DSK1 OS\ X\ Base\ System
   getdsk DSK2 MyVolume
   diskutil unmountdisk $DSK1
   diskutil unmountdisk $DSK2
   sudo dd if=$DSK1 of=$DSK2 bs=1m
   diskutil eject $DSK1
   diskutil unmountdisk $DSK2
   diskutil mountdisk $DSK2
   

    

   Note: Since the original will be immediately ejected and eventually deleted, I did not bother to use the hfs.util command to change the UUID of the clone.

You can now proceed with the rest of the steps.

---

References

How do I make a bootable USB flash drive on a Mac?
What is the best way to generate a Yosemite or Mavericks Install USB flash drive?
Install El Capitan with VirtualBox on OS X

Answer 2

I was stuck in this very same situation for a while now and have found a way to create an install media (installing while we speak) on MacOS Catalina. A bit of Terminal magic is required, but nothing too fancy.

I will create a temporary folder on the Desktop so it is easier to inspect the structure with finder.

Steps to take to get the command running as suggested in https://support.apple.com/en-sg/HT201372

1. Download and mount the image for El Capitan (e.g. double click onto the .dmg file)
2. Open the Terminal app
3. (optional) Change to the Desktop cd ~/Desktop
4. (optional) Create a temporary folder mkdir installCapitan && cd installCapitan
5. Extract the installer here xar -xf /Volumes/Install\ OS\ X/InstallMacOSX.pkg
6. Change into the resulting folder, with cd InstallMacOSX.pkg
7. Now you're greeted with several files, e.g. Payload, Scripts, InstallESD.dmg
8. Unpack Payload with tar xvzf Payload
9. Now you have the Install OS X El Capitan.app Apple talks about in the link above
10. One more step, move the install data to where it should be: mv InstallESD.dmg Install\ OS\ X\ El\ Capitan.app/Contents/SharedSupport/

Now running the createinstallmedia command should work when given the right paths, and this should work:

sudo Install\ OS\ X\ El\ Capitan.app/Contents/Resources/createinstallmedia \
        --applicationpath ./Install\ OS\ X\ El\ Capitan.app \
        --volume /Volumes/my_install_volume

Change your installation volume path accordingly and be careful to pick the right one, otherwise loss of data may occur.

edit: If your installer fails with something about not being able to verify the install media, check this answer out, it helped me: https://apple.stackexchange.com/a/232016/371520

Good luck

Answer 3

No VM, No asr + Fix for InstallESD.dmg

~ Tested on Monterey for El Capitan ~

---

WARNING

It is not secure to use unsupported, outdated operating systems like El Capitan, assuming you connect them to the Internet.

• You have many options to mitigate or even avoid this insecurity altogether, but that is a whole other topic.

---

1. Apple tries to force you to download the dmg with Safari. When I tried to download with Chrome, nothing happened; I didn't even get an error saying what was wrong. Download with Safari

2. We're going to bypass the "supported platform" check by unpacking the downloaded pkg file (in the dmg), removing the check, and then repacking. Create an El Capitan directory to unpack into.

3. Extract Credit

   • Double-click the dmg you downloaded. A handy window pops up. Keep it open for now.
   • Open Terminal and cd into the El Capitan directory you made
     • You can drag the directory into Terminal after cd to auto-insert the path
   • tar -xf /path/to/InstallMacOSX.pkg Substitute your path to the pkg (not the dmg -- but again, the pkg is in the dmg)
     • Example: xar -xf /Volumes/Install\ OS\ X/InstallMacOSX.pkg
       • I just typed xar -xf and then dragged the pkg from the Finder window into Terminal to auto-insert the path
       • The /Volumes/Install\ OS\ X part was my path to the dmg mount point.

4. Remove "supported platform" check

   • In the El Capitan directory, right-click Distribution > Open With > Other..., search for "text"..., select "TextEdit", and click the "Open" button.
   • Search (cmd+f) for m(){ (no spaces). That should land you on a line that says function isSupportedPlatform(){. Delete all the lines between, but not including, the aforementioned line and the closing }, which is the very next } to be in the first column. Or, instead of deleting these lines, comment them out using JavaScript comment syntax. Between the function... line and the }, put return true;. Don't forget the semi-colon. Save. So you should now have:

function isSupportedPlatform(){
    return true;
    
    /*
    (And maybe you kept the original code as a comment.)
    */
}

5. You can close the TextEdit window for Distribution. Now we'll repack. Assuming your Terminal is still in El Capitan: xar --compression none -cf /desired/path/ElCapitan.pkg . That ending period is actually a part of the command. Replace the path with where you want your modified pkg. Credit

6. Double-click the modified pkg you just made. Click "Allow" in the pop-up. Click "Continue". Click "Install". Authorize (fingerprint, password, whatever). Close.

   • If you get an error, double-check your changes to Distribution. Did you save? Semicolon? Improperly commented-out code (*/ vs /*, etc.)?

7. Open Applications in Finder. "Install OS X El Capitan" is in there. Right-click it, "Show Package Contents". Then open Contents > SharedSupport. For me, "InstallESD.dmg" was not properly recreated. Go ahead and double-click it to see if you need to fix this as did I. I got a pop-up with error code 3840. Leave this Finder window open. If you got an error, move the faulty dmg to trash. This will require authorization. If it did open, unmount by dragging its virtual drive from your Desktop (wallpaper area) to the trash icon in your dock.

8. Assuming you had to delete that InstallESD.dmg file, click your Finder window and press cmd + n to open a new window. In the new window, navigate to your El Capitan directory, right-click "InstallMacOSX.pkg" and "Show Package Contents". You should now see an "InstallESD.dmg" file. Fun fact: the pkg in the original dmg, also called "InstallMacOSX.pkg", does not give "Show Package Contents" as an option when you right-click it. Copy and paste the InstallESD.dmg file into SharedSupport, in your other Finder window. This will again require authorization.

9. Now you can finally run the command to create a drive bootable into the El Capitan Installer. Replace /Volumes/MyVolume with the mount point of the drive you wish to use. It will erase the drive.

   • sudo /Applications/Install\ OS\ X\ El\ Capitan.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume --applicationpath /Applications/Install\ OS\ X\ El\ Capitan.app
     • sudo (root) is needed to reformat the drive

10. Don't forget to delete all the El Capitan stuff off your computer when you're done. This how-to took a lot of drive space.

• The original dmg
• The modified pkg
• Your El Capitan directory
• "Install OS X El Capitan" in Applications
• And delete them out of your Trash, if applicable

Answer 4

Apparently under certain circumstances, Apple now requires the use of "VMware Fusion Player" to create an USB flash drive El Capitan bootable installer. Fortunately, the "VMware Fusion Player" is now a free product when used for Non‑Commercial activity.

Below are the basic requirements for a Mac being used to create the El Capitan USB flash drive installer.

• The Mac is Intel Based
• The Mac meets the Mac hardware requirements published in the Apple document "OS X El Capitan - Technical Specifications".
• The Mac is running OS X v10.6.8 or later (which includes any version of macOS).

Below are the steps needed to create an USB flash drive El Capitan bootable installer.

1. Download the InstallMacOSX.dmg file by clicking on the OS X El Capitan 10.11 link in the Apple document "How to download macOS". These instructions assume that this file has been downloaded to your ~/Downloads folder.

2. Use the Finder application to open the ~/Downloads/InstallMacOSX.dmg file with the DiskImageMounter application.

3. Use the Finder application to open the InstallMacOSX.pkg file in the Install OS X volume with the Installer application. If you get the popup message "This version of OS X 10.11 cannot be installed on this computer.", then proceed to the next step. Otherwise, the Install OS X El Capitan application should have been successfully created in the /Applications folder. If necessary, from the sidebar of a Finder application window, choose to eject the Install OS X volume. Close all Finder application windows, then skip to the last step.

4. In the popup window, select the Close button. From the sidebar of a Finder application window, choose to eject the Install OS X volume. Close all Finder application windows.

5. Goto the "VMware Fusion Player – Personal Use License" website, create an account and get a free VMware Fusion Player license. Download and install the VMware Fusion application. These instructions were tested using "VMware Fusion Player" version 12.1.0.

6. Choose a version of macOS to install. For example, a virtual machine can be installed by using an Install macOS application or macOS Recovery partition compatible with your Mac. Versions of macOS are available in the App Store or by following the instructions in the Apple document "How to download macOS".

   Note: Installing the oldest compatible version of macOS usually results in a virtual machine with best performance.

7. Open the VMware Fusion application. If a window similar to the one shown below does not automatically appear, then select File→New… from the menu bar.

   

   Note: These instructions were tested using macOS 11.1 (Big Sur) on 2018 Mac mini as the host. The Install macOS Big Sur application for macOS 11.1 was already downloaded to the /Applications folder. You may wish to choose a different installation method and/or a different version of macOS.

   Use the Finder application to drag and drop the Install macOS Big Sur application from the /Applications folder to the window, as shown below. When finished, select the Continue button.

   

   When a window similar to the one shown below appears, select the Customize Settings button. Save the new virtual machine and wait for the installation medium to be created.

   

   When a window similar to the one shown below appears, select Advanced.

   

   When a window similar to the one shown below appears, look for a Disable Side Channel Mediations checkbox. If one is found, then check the box, as shown below.

   

   When finished, select the Show All button, then select Network Adaptor. When a window similar to the one shown below appears, select the Autodetect radio button, as shown below.

   

   Close the window by selecting the red dot in the upper left corner of the window. Before proceeding, note the following.

   • You may wish to temporarily modify the settings in the Energy Saver pane of the System Preferences application to prevent the host from sleeping during the macOS installation on the client.
   • You will not need to use the Disk Utility application to initialize the internal drive on the client.
   • When asked to sign in with your Apple ID, you can select to setup up later, then when asked to create a computer account, enter a local account name and password.

   Find the window with the big start button, as show below. Select the start button and complete the installation of macOS.

   

8. (Optional) Install "VMware Tools" for convenience. On the host, select Virtual Machine→Install VMware Tools from the menu bar of the VMware Fusion application.

9. (Optional) Use the client to perform this step. Download the InstallMacOSX.dmg file by clicking on the OS X El Capitan 10.11 link in the Apple document "How to download macOS". Use the Finder application to open the ~/Downloads/InstallMacOSX.dmg file with the DiskImageMounter application, then open the InstallMacOSX.pkg file in the Install OS X volume with the Installer application. Install the Install OS X El Capitan application on the Macintosh HD disk. When finished, from the sidebar of a Finder application window, choose to eject the Install OS X volume. Skip the next two steps.

10. On the host, open the Sharing pane of the System Preferences application and make sure File Sharing is highlighted and checked off. Note the URL where other users can access shared folder on the this computer, and administrators all volumes. This URL will start with smb://.

11. On the client, select Go→Connect to Server… from the menu bar of the Finder application. Enter the URL noted in the previous step, then select the Connect button. If a "Your are attempting to connect to the server" popup occurs, then select the Connect button. After entering the Name and Password for your account on the host, select the Connect button. Choose to mount your home folder on the host, then select OK. Use the Finder application on the client to open the InstallMacOSX.dmg file in your ~/Downloads folder on the host with DiskImageMounter application, then open the InstallMacOSX.pkg file in the Install OS X volume with the Installer application. Install the Install OS X El Capitan application on the Macintosh HD disk. When finished, from the sidebar of a Finder application window on the client, choose to eject the host server. This should also eject the Install OS X volume. If desired, turn off File Sharing on the host computer. If a "There may be users connected to this computer." popup occurs, then select the OK button. On the host, quit the System Preferences application.

12. (Optional) At this point, You can insert a 8 GB or larger flash drive in a USB port on the host. When a popup similar to the one shown below appears, select Connect to the VM, then skip to the last step and use the client to create a bootable installer for macOS.

    Note: Before using this step, you may want adjust the USB Compatibility settings for the client virtual machine.

    

13. On the client, open the Sharing pane of the System Preferences application and make sure File Sharing is highlighted and checked off. Note the URL where other users can access shared folder on the this computer, and administrators all volumes. This URL will start with smb://.

14. On the host, select Go→Connect to Server… from the menu bar of the Finder application. Enter the URL noted in the previous step, the select the Connect button. If a "Your are attempting to connect to the server" popup occurs, then select the Connect button. After entering the Name and Password for your account on the client, select the Connect button. Choose to mount the Macintosh HD volume, then select OK. Use the Finder application on the host to copy the Install OS X El Capitan application from the /Applications folder on the client to the /Applications folder on the host. When finished, from the sidebar of a Finder application window on the host, choose to eject the client server. If desired, turn off File Sharing on the client computer. If a "There may be users connected to this computer." popup occurs, then enter 0 for Minutes and select the OK button.

15. On the client virtual machine, quit the System Preferences application and close all Finder application windows, then shutdown. If desired, delete the virtual machine. Quit the VMware Fusion application.

16. Follow the instructions in Apple document "How to create a bootable installer for macOS" to create the macOS USB flash drive installer. The flash drive must be at least 8 GB in size.

References

• Cannot create a new VM from DMGs provided by Apple in October 2019
• OS X El Capitan - Technical Specifications
• How to download macOS
• VMware Fusion Player – Personal Use License
• How to create a bootable installer for macOS

Answer 5

The answer is that there appears to be a problem with Catalina creating an installation app for other versions of OSX-certainly with El Capitan from the issue here. Solution was to follow the Apple supplied procedure https://support.apple.com/en-sg/HT201372 but on another version of OSX-Sierra worked in this case.

Answer 6

I don't have enough reputation points to vote or comment on Chris Braucker solution, but seems to be working for me.... writing to USB stick as we speak after multiple hours of trying to find way of getting Catalina to create bootable USB drive for El Capitan.

One extra step (5b) might be added for relatively unsophisticated terminal users, that took me a while to figure out. After Step 5, you're not presented with the folder with payload in it. You first have to do cd InstallMacOSX.pkg to get inside this folder and see the payload file

Answer 7

I presume that you want to create a bootable El-Capitan USB installer? Maybe can check this guide from Apple?

https://support.apple.com/en-sg/HT201372

Answer 8

This answer assumes you want the El Capitan USB installer to install El Capitan on an older Mac capable of running Snow Leopard (OS X 10.6). In this case, you can solve the problem by using the older Mac to create the El Capitan USB installer.

Note: In this answer the Catalina (or post-El Capitan) installed Mac is referred to as the newer Mac and the Mac where El Capitan is to be installed is referred to as the older Mac.

These instruction will require you to use the newer Mac to do the downloading. Use an USB flash drive or file sharing to transfer downloads to the older Mac.

Here are the steps to follow.

1. Get Snow Leopard 10.6 installed on the older Mac. Use the newer Mac to create USB flash drive bootable Snow Leopard 10.6 installer from a downloadable ISO. See this question.
2. Upgrade the older Mac to OS X 10.6.8. See this Apple article
3. Use the older Mac to create the Install OS X El Capitan application from the InstallMacOSX.dmg file. See this Apple article.
4. Use the older Mac to create the El Capitan USB installer. See this Apple article.

Note: You probably could avoid creating the El Capitan USB installer the and just run the Install OS X El Capitan application on the older Mac.