Unable to update macOS Catalina on 2013 iMac

I'm trying to update the Operating system from High Sierra to Catalina. In the middle of the update it just stopped about 40% through with the message estimated time remaining and it never finishes. If I restart the computer it just continues to this same point over and over.

It does load into bootcamp fine, but not the Mac partition.

Any ideas?

[Re-Titled by Moderator]

Original Title: Issues updating 2013 21" iMac

iMac 21.5″, macOS 10.14

Posted on Jun 12, 2025 05:55 PM

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1 reply

a brody

Level 10

85,257 points

Jun 21, 2025 03:55 PM in response to lanza06

Have you backed up your data on your Mac to two distinct locations? If not, I would stop right there, and backup your data first.

It may be there is some aging or corruption on your Mac OS partition.

It may also be there is insufficient space.

Etrecheck - the handy reporting tool for … - Apple Community

Should help us isolate why you are having issues.

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Unable to update macOS Catalina on 2013 iMac

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