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'Checking (null)' during mac OS update

Had to reformat my 2017 Macbook Pro. That re-installed High Sierra. Update to Mojave worked fine as well. Now trying to go to Catalina (or Big Sur) i get a checking (null) error and the installer essentially freezes here.


I have spoken with multiple support reps and tried all of the recommended fixes.


Has anyone found a workaround or fix to this issue? Seeing multiple threads open that haven't been solved.

MacBook Pro 13″, macOS 10.14

Posted on Dec 6, 2021 9:28 AM

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Posted on Dec 7, 2021 2:31 AM

The check NULL error message is sometimes related to an Existing Installer ( failed ) still present on the computer either in the Download Folder or and in the Applications folder. In either case - suggest exploring this and if present, drag and drop to trash and empty Trash


To start again to grab either of the to afore mentioned upgrades - suggestion. Restart in Safe Mode Shift key immediately at restart. For best results. connect via Ethernet Cable to Router. Once operational How to get old versions and using Safari ( again best results ) commence to download again.

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Question marked as Top-ranking reply

Dec 7, 2021 2:31 AM in response to Elli0t7

The check NULL error message is sometimes related to an Existing Installer ( failed ) still present on the computer either in the Download Folder or and in the Applications folder. In either case - suggest exploring this and if present, drag and drop to trash and empty Trash


To start again to grab either of the to afore mentioned upgrades - suggestion. Restart in Safe Mode Shift key immediately at restart. For best results. connect via Ethernet Cable to Router. Once operational How to get old versions and using Safari ( again best results ) commence to download again.

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'Checking (null)' during mac OS update

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