Disk image will not mount: "broken pipe" errors and more
What to do when a Mac OS X disk image will not mount.
[Published Thursday, July 5th]
In some cases, a disk image will not mount in Mac OS X, giving the error message "Unable to mount disk. Broken pipe," or another. There are various potential solutions for this problem:
Use Disk Utility's "Restore" function Follow these steps to use Disk Utility's Restore function to extract the contents of a disk image:
Re-download Simply delete the afflicted disk image, re-download from the original source and re-attempt mounting.
- Launch Disk Utility (located in /Applications/Utilities and select a mounted volume (such as your startup drive)
- Click the Restore button
- Drag the problematic disk image from the Finder into the Source field, or click the Image... button and locate it.
- Drag the drive on which you would like to place the files from the left-hand bar to the Destination field. (Make sure that the Erase destination box is not checked).
- Click the Restore button
- The files contained on the disk image should appear at the root level of the selected destination drive.
Boot in Safe mode If you are having a problem where disk images won't mount, try booting in Safe Mode (by holding down the Shift key while starting up), then re-attempting mounting of the disk image.
Delete kernel extension caches Delete the following files:
- /System/Library/Extensions.kextcache
- /System/Library/com.apple.kernelcaches
then restart, and re-attempt mounting.
Use an alternate tool Mount.app, FlashMount, or Toast Titanium can all sometimes succeed in mounting disk images where Mac OS X and Disk Utility fail.
You may also want to try using Pacifist to view and extract the contents of a disk image.
Re-apply combo updater Try re-applying the most recent Mac OS X combo updater from Apple's download page and re-attempting mounting.
Duplicate and force Apple has posted a Knowledge Base article (#305111) detailing an issue where users may receive the error message "Disk image you are opening may be damaged..." when attempting to mount disk images under Mac OS X 10.4.9. According to Apple, Mac OS X 10.4.9 is more robust in its ability to detect damaged or corrupted disk images. However, you may encounter this error when working with ostensibly functional disk images. The Knowledge base articles offers a process for dealing with the disk images identified as damaged, which involves first duplicating the disk image then forcing a mount by clicking the "Open" button when the error message appears; see the Knowledge Base article for further details.
Feedback? Late-breakers@macfixit.com.
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