First Aid Failure

First Aid usually unmount a drive before running and inspecting it, so First Aid still runs with an unmounted drive in many instances.

You could try erasing and reformatting the drive (via Disk Utility), as that will create a new partition map that fits. This presumes you have backups of all of the files and folders on that drive.

If you have filled the drive to capacity such that it cannot expand the partition map to accommodate additional files, the drive might be unusable until reformatted. However, filling it up again would cause the same problem.

Or as leroy suggests, the drive might be failing in which case it is best to replace it (instead of reformatting it and trying to continue using it). I tend to be fairly conservative about drives and as soon as they start behaving questionably, I replace them. In my experience, this does not happen often but no drive lasts forever. Alternatively, erase/reformat and try to continue using but always keep good backups of any content you put on it (a good practice anyway).

worx25 wrote:

I ran First Aid on an external hard drive (3.5") and it failed. The Details include this statement: "The partition map needs to be repaired because it is too large for its container disk.: (-69660)".

The drive will not mount. Is there a way to fix this?

How did you get a report if it is not mounted(?)

If you can not force mount the external drive....(?)

DiskUtility>View>Show All Devices erase/reformat/initilize as new the Parent drive (ie top most)—this will erase all data

Erase and reformat a storage device in Disk Utility on Mac - Apple Support

ref:

https://apple.stackexchange.com/questions/305071/force-mounting-an-external-disk-that-is-not-recognized

Trying to Force Mount in Terminal - Apple Community

force mounting a hard drive - Apple Community

you can —

try connecting to a different port

try a different cable connection

try a different enclosure

if the drive has failed replace it