Mount of outer dmg failed

[TomHsiung]

Hey all,

I keep getting this error. I have formatted my usage to GUID. And have downloaded the El Crapitan Beta, but overtime I try to do the sudo copy method. I get Mount of outer dmg failed.

Is it as easy as getting a different usb stick or could it be the physical usb port needs to be different? Or, could it be a bum download?

The most likely issue is , well, the most likely issue, I just don't know what it would be.

I have exactly the completely same issue. See the screenshot.

 

[TomHsiung]

From where did you download the Public Beta?

From Apple Store.

 

[cmn699]

I have exactly the completely same issue. See the screenshot.

View attachment 144244

I had the EXACT ERROR when I tried to create the USB Installer in Yosemite in 4 PCs with different Motherboards. In one of my computers I still have a Mountain Lion, in addition to, Yosemite 10.10.4, Mavericks, Windows8.1, Ubuntu Studio 15.04 running from separate disks. When I transferred the same OS X 10.11 installer file from Yosemite to Mavericks [ in 2 computers] the same error occurred . I played around with different brands of FDs and both 8GB and 16GB FDs without any success. But once I got the file to Mountain Lion, to my surprise I had flawless installation on the USB FD. I used all the Flash drives previously showed that error and all of them worked! I am convinced the above error was not due to any file corruption during download of the El Capitan install software and not due to brand of FD or their sizes. But I have no explanation why the error occurred in 4 Yosemite installation and two Mavericks but none of the 3 Mountain Lion!.
I have installed El Capitan on the following Motherboards & CPUs with different USB Installers created in ML with varying difficulties but more or less fully functional except for some software like MS Office 2011, Firefox Ver39,and VLC Media Player that I have tested so far.

• GA-Z77X-UP4-Th + i7+ PEG: Radeon 7000 Series[I have posted that on the Forum] ,
• GA-Z97X-UD5h +i7+ IGFX: IntelHD4600 +i7
• MSI-Z77A-G45 +i7+IGFX: IntelHD 3000

 

[MidnightX]

Actually, the attached worked for me (see attached image):

• Re-download Public Beta from App Store
• In Terminal type sudo su press return
• Then type the /Applications etc... command

View attachment 144061

I am trying this right now. I have never had this kind of problem trying to make a bootable USB of Mac OS till now. I only get my Mac OS from the Apple Store. I will let you know how that works. I've only downloaded it from the App store for the 2nd time after it failed the first few trys.

 

[Quade321]

Has anyone tried doing this the manual way instead of using createinstallmedia? (I never liked createinstallmedia, it seemed like installation times were longer and stuff was a bit stranger)

Anyway, manual creation is easy
-Open /Applications/Install OS X El Capitan Public Beta.app/Contents/SharedSupport/InstallESD.dmg
-Open /Volumes/OS X Install ESD/BaseSystem.dmg (It's hidden! So you could just open it with Terminal or use the command below to show your hidden files)
-Restore BaseSystem to your flash drive using Disk Utility
-(Optionally) Right click your flash drive in Disk Utility, click show in finder, and then rename it for ease
-Delete the Packages alias in /Volumes/(Your Flash Drive)/System/Installation/
-Copy Packages from OS X Install ESD in place of the alias you deleted
-Copy BaseSystem.dmg and BaseSystem.chunklist from OS X Install ESD to the root of your flash drive
-Install Clover, or a boot loader of your choice!
(Just trying to give a quick rundown as this isn't exactly supposed to be a tutorial thread, and I'm trying to not spam)

Unhide files: defaults write com.apple.finder AppleShowAllFiles TRUE;killall Finder
Hide files: defaults write com.apple.finder AppleShowAllFiles FALSE;killall Finder

Anyway, I assume this method avoids the issue that caused this thread to be opened, so worth a shot. I always use this method for creating my OS X USBs for use with Clover (Yosemite and El Capitan), and it always works fine for me. Hope this helps!

 

[MidnightX]

Has anyone tried doing this the manual way instead of using createinstallmedia? (I never liked createinstallmedia, it seemed like installation times were longer and stuff was a bit stranger)

Anyway, manual creation is easy
-Open /Applications/Install OS X El Capitan Public Beta.app/Contents/SharedSupport/InstallESD.dmg
-Open /Volumes/OS X Install ESD/BaseSystem.dmg (It's hidden! So you could just open it with Terminal or use the command below to show your hidden files)
-Restore BaseSystem to your flash drive using Disk Utility
-(Optionally) Right click your flash drive in Disk Utility, click show in finder, and then rename it for ease
-Delete the Packages alias in /Volumes/(Your Flash Drive)/System/Installation/
-Copy Packages from OS X Install ESD in place of the alias you deleted
-Copy BaseSystem.dmg and BaseSystem.chunklist from OS X Install ESD to the root of your flash drive
-Install Clover, or a boot loader of your choice!
(Just trying to give a quick rundown as this isn't exactly supposed to be a tutorial thread, and I'm trying to not spam)

Unhide files: defaults write com.apple.finder AppleShowAllFiles TRUE;killall Finder
Hide files: defaults write com.apple.finder AppleShowAllFiles FALSE;killall Finder

Anyway, I assume this method avoids the issue that caused this thread to be opened, so worth a shot. I always use this method for creating my OS X USBs for use with Clover (Yosemite and El Capitan), and it always works fine for me. Hope this helps!

That worked to make a bootable USB drive! I had El Capitan Installed and its way to buggy for my hardware.

The show hidden file command is wrong but I did find the correct one.

 

[Quade321]

That worked to make a bootable USB drive! I had El Capitan Installed and its way to buggy for my hardware.

Aw. :\

The show hidden file command is wrong but I did find the correct one.

Oh, sorry. I think it changed between a few different versions of OS X. That's the one that works for me under Yosemite.

 

[TomHsiung]

I used another usb stick and the issue resolved spontaneously.

Tom

 

[BreBo]

Actually, the attached worked for me (see attached image):

• Re-download Public Beta from App Store
• In Terminal type sudo su press return
• Then type the /Applications etc... command

View attachment 144061

Same here, and I didn't re-download from the App Store.

 

[custommademac]

If you are using USB 3.0 drive, move this one to USB 2.0 port en try again ! After I did that it all went well ! Cheers !