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Erase failure

I'm wiping an older iMac (Catalina) for disposal. I followed the instructions in support doc HT201065 and it appears to have erased the HD - Data partition, but not the system part. When I try to reinstall Catalina or reinstall from Time Machine backup, it fails, saying I have an incomplete system.


What do I try next?


Thanks in advance.


Rob

iMac 27″, macOS 10.15

Posted on Aug 24, 2021 10:47 AM

Reply
Question marked as Top-ranking reply

Posted on Aug 24, 2021 10:58 AM

Sometimes you have to go thru the erasure in steps with Disk Utility.




Try this:


1 - make sure E is mounted and then erase.

2 - make sure D is mounted and then erase.

3 - select C and erase.

4 - select B and erase;

5 - finally select A and erase.


This has worked for me. The key is making sure the early volumes are mounted and sometimes that takes unmounting them and then remounting before erasing.


3 replies
Question marked as Top-ranking reply

Aug 24, 2021 10:58 AM in response to rcpfaff

Sometimes you have to go thru the erasure in steps with Disk Utility.




Try this:


1 - make sure E is mounted and then erase.

2 - make sure D is mounted and then erase.

3 - select C and erase.

4 - select B and erase;

5 - finally select A and erase.


This has worked for me. The key is making sure the early volumes are mounted and sometimes that takes unmounting them and then remounting before erasing.


Erase failure

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