"OS X Can't Start up from this disk"

[jrk]

Strange, you don't have EFI partition?

Indeed, this is what got clobbered by a Windows 8 install on a separate drive, but without remembering to unplug the Mac OS drive. The rewritten EFI partition always booted into Windows (on the other drive), or failed to boot (if that drive was removed), but this behavior went away simply by deleting the EFI partition. Chameleon still worked fine.

Is there a method to restore a Chameleon/Unibeast-styled EFI partition, as you would get on a fresh Unibeast install?

 

[nguyenmac]

Indeed, this is what got clobbered by a Windows 8 install on a separate drive, but without remembering to unplug the Mac OS drive. The rewritten EFI partition always booted into Windows (on the other drive), or failed to boot (if that drive was removed), but this behavior went away simply by deleting the EFI partition. Chameleon still worked fine.

Is there a method to restore a Chameleon/Unibeast-styled EFI partition, as you would get on a fresh Unibeast install?

Can you upgrade to Mavericks now?

 

[jrk]

No. Clobbering the Windows-created EFI partition was done two months ago. That may be the source of this trouble. I can't figure out how to add back an EFI partition. The space exists at the start of the drive, but I'm not sure how to recreate it.

 

[nguyenmac]

No. Clobbering the Windows-created EFI partition was done two months ago. That may be the source of this trouble. I can't figure out how to add back an EFI partition. The space exists at the start of the drive, but I'm not sure how to recreate it.

Use gparted from linux USB to create a small (min 100MB) FAT32 partition at the begin of your disk. Be caution that you should back up all your data before messing up with disk.

 

[RehabMan]

No. Clobbering the Windows-created EFI partition was done two months ago. That may be the source of this trouble. I can't figure out how to add back an EFI partition. The space exists at the start of the drive, but I'm not sure how to recreate it.

You could try in gparted, but I'm not sure of all the tricks. Might have to throw a bit of 'gdisk' in there to get the type correct (EE).

Whatever you do, make a backup in case you have to install completely fresh.

One brute force way would be to:
- make an image of your current os x partition (to external hard drive)
- repartition in Disk Utility
- clone from the image you made back into the new empty os x partition
- update to Mavericks

 

[faithie999]

You could try in gparted, but I'm not sure of all the tricks. Might have to throw a bit of 'gdisk' in there to get the type correct (EE).

Whatever you do, make a backup in case you have to install completely fresh.

One brute force way would be to:
- make an image of your current os x partition (to external hard drive)
- repartition in Disk Utility
- clone from the image you made back into the new empty os x partition
- update to Mavericks

+1
i agree with RehabMan. if it were me i would do this rather than trying to install an efI partition on an existing drive.

after you clone, run the probook installer and install chimera to the clone so it will boot.

 

[RehabMan]

after you clone, run the probook installer and install chimera to the clone so it will boot.

+1, but install Chameleon instead... using the ProBook Installer, of course.

 

[jrk]

Indeed, I was already in the process of imaging the drive for potential reformatting. In the end, this is the route I took.

The one downside: reformatting, restoring, and installing over, together, seem to have changed the identity of the machine such that I was locked out of iMessage, needed to re-authorize with the App Store, fully rebuild my Dropbox index, lost continuity of Time Machine backups, and other such annoyances.

 

[knox]

I'm getting the same error on OSx El Capitan.. I upgraded from mavericks to yosemite last year and the error wasn't there then.
What could be the problem, I have a GPT and an EFI Partition

 

[RehabMan]

I'm getting the same error on OSx El Capitan.. I upgraded from mavericks to yosemite last year and the error wasn't there then.
What could be the problem, I have a GPT and an EFI Partition

If you're getting the error I'm thinking of... It is normal. Ignore it.

Otherwise, please clarify "same error".