Saturday, February 25, 2012

Tutorial: How To Uninstall Mountain Lion OS X

Story: I have a problem of downloading and installing any new Apple product once it comes out and so I downloaded and installed Mountain Lion OS X on my main machine (MacBook Air) and then I realized that it had a lot of problems and a lot of my programs were having not compatible with it, so I tried to uninstall it. I ran into a lot of trouble and there was not a lot of good info online and it took me a long time how to figure out (14+ hours), so I thought I would write a blog post so other people wouldn't have to go through the same trouble. This blog post is short because I have a ton of homework and life stuff so I just put the most essential info in it.

1. I first tried to log into my Mac Developer Account and download Mac OS X Lion through the Mac App Store, but the installer will tell you that you can't install Mac OS X Lion because you have a newer version of Mac OS X installed.

2. I then obtained the Install Mac OS X Lion through another means (you should find some way to get this). Note: You have to get Mac OS X Lion 10.7.2 or above.

Once I obtained it if you double click the installer nothing will happen. Right click the app and click show package contents.

3. Go to Contents > SharedSupport > OSinstall.mpkg and double click the package and you will get this error.

4. In Finder search for the Disk Utility App and create a partition for Mac OS X Lion.

5. Once you create a partition you have to open Terminal to change the Mac OS X version number so you can install Mac OS X Lion on the partition. 


6. To change the Mac OS X version number you have to change the settings of the file /System/Library/CoreServices/SystemVersion.plist and then modify it in a text editor. 



7. Then you should be able to run the installer and install Mac OS X Lion on the disk partition. I think this worked for me. If not drag and drop the package contents of the installer app into the new partition and then restart your computer and load the new disk partition. (Restart the computer and hold the option button and then select the correct disk partition) Do not restore the Mac OS X Lion disk image into the disk partition. 

8. If you could not run the Mac OS X Lion installer from OS X Mountain Lion, mount the disk image and copy the entire contents of that into your new disk partition, and then load that on startup. 

Note: If you get errors about the disk being locked you did something wrong. Create a brand new partition and drag and drop the installer package contents into the new disk partition, and then restart the computer. 


Vineet said...

So by running the 10.7 installer this way, will it overwrite 10.8? Does rails work for you now that you have gone back to 10.7?

mosawi said...

Thank you soo much ktran! you seriously saved my life. 10.8 kept on crashing on me every time I launched virtual box.

Anonymous said...

Dear Sir, thanks for the instructions!

Will I be able to delete the Mountain Lion partition and keep Lion (10.7) with the modified firmware (which changed because of 10.8) ?

Simon said...

Anyone any links to a direct download for a certain osx lion installer? I did have the installer as a legal download but for some reason the app store wants to charge me for it again :/

Arr MiHardies said...

by simply changing the system version as described above, I was able to download Lion from the app store.

jimi said...

I truly relish whilst I go through your blogs and articles. ipad tablet

Technology Blog said...

Ruby on rails works for me.

Technology Blog said...

I can't give you a percise answer, but it worked fine for me.

city said...

thanks for sharing.

Emmanuel Blethy said...

i am unable to modify the sys version somehelp. do i copy whatever is in the step 6 screen shot

Technology Blog said...

Make sure you typed sudo before the command.