Disk Utility on iMac 11.5.2 - unable to repair external SSDs

as per the above - all my external SSDs used as time-machine back-ups failed when using Disk Utility to repair them. It says that DU successfully unmounted them but fails with code; (-69845)

I should add that each SSD appears to make a complete backup of my iMac which i can then access or restore much like my time capsule can.

Each SSD has been formatted as; GUID partition Map in APFS Containers.

My iMac is a 27" (late 2015 model) running 11.5.2 OS

iMac 27″, macOS 11.5

Posted on Aug 23, 2021 2:29 AM

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2 replies

Aug 23, 2021 2:53 AM in response to Owl-53

> Reformat as HFS Journaled / GUID Partition Map. Then reformat back to APFS / GUID Partition Map

I have also heard that sometimes the partition map might need resetting so, when given a chance to nuke everything, I have reformatted the device temporarily as FAT (Master Boot Record) and then back to MacOS Extended/APFS (GUID). Does anyone know whether it is necessary to switch to another partition scheme (GUID <-> Master Boot Record) when doing so?

Owl-53

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Aug 23, 2021 2:45 AM in response to ribbo39

Only a suggestion - Reformat as HFS Journaled / GUID Partition Map. Then reformat back to APFS / GUID Partition Map. Doing so, just might remove a bad partition mapping when put back to APFS format.

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Disk Utility on iMac 11.5.2 - unable to repair external SSDs