macOS Mojave Security Update 2021-003 10.14.6

macRumors supplied the probable cause and fix... i hope.

caused by using mojave as source for catalina migration to a separate boot partition

have to install macOS Mojave 10.14.6 Combo Update over existing mojave... then reinstall newer updates

what a pain!

thanks for the reply

so far as i can tell, the migration leaves the source mojave volume with a catalina restore partition... macOS Base System 10.15.x

that's a bug in my book.

Already, finished a reinstall to a fresh partition an cloned back to original.

4 hours i'll never get back

indeed, here's the text of the SystemVersion.plist file on the recovery volume of the Mojave source partition post Catalina update to separate partition via Software Update panel...

looks like confirmation the Recovery volume of the Mojave source has been swapped with 10.15.7 system.

Good to have multiple clone backups.

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">

<plist version="1.0">

<dict>

<key>ProductBuildVersion</key>

<string>19H524</string>

<key>ProductCopyright</key>

<string>1983-2021 Apple Inc.</string>

<key>ProductName</key>

<string>Mac OS X</string>

<key>ProductUserVisibleVersion</key>

<string>10.15.7</string>

<key>ProductVersion</key>

<string>10.15.7</string>

<key>iOSSupportVersion</key>

<string>13.6</string>

</dict>

</plist>

Thanks for the suggestion, but i've completely reinstalled, and all is well aside from my annoyance.

This is a bug alert from my point of view.

in a nutshell: i have both mojave and catalina installed and switch between the two due to an extremely useful 32bit app.

A update/migration of mohave > catalina in a separate catalina partition resulted in the mojave partition's recovery volume being overwritten/superseded by a catalina recovery system 'macOS Base System 10.15....' .

So, the next system wide update, that apparently requires booting to the recovery volume, failed... you can't boot in catalina and install mojave.

When the install fails... opening disk utility from the menu, before rebooting, showed the install booted in catalina recovery.

If i had know about the recovery volume swap, i could have easily recovered from a clone of the mojave partition in less than 20 minutes.

In my opinion, this is a bug in the catalina install.

In my case, i first booted in os sierra and simply mounted the recovery volume, navigated into the single folder and read the system info.plist

If you have an update to mojave that fails and a install dialog window appears displaying an error code below the round catalina 'badge'... your recovery volume's 'base system' is almost certainly catalina.

You can confirm, by opening Disk Utility using the menu above the 'error dialog'... the boot volume name will be displayed there.

I'm no expert, just a long time user with too much time on my hands.

final thought for now:

content of the recovery volume has zero impact on day-to-day use.

i would not be surprised if this latest security update to mojave is the last.

if one has chosen to 'share' with apple, i suspect they may offer an automatic update to install correct base system to recovery volume.

Can easily mount a APFS recovery volume and read the 'SystemVersion.plist' then unmount from a terminal window using 'diskutil' command

the 'recovery' volume will not appear on the desktop.

'diskutil list' to get a list of volumes with identifiers like the following...

"APFS Volume Recovery                522.9 MB   disk2s3"

the identifier is the right most column... 'disk2s3' in the example above

replace [[disk identifier]] in the line below with the actual disk identifier

diskutil mount [[disk Identifier]]; find /volumes/recovery -type f -name SystemVersion.plist -exec cat \{\} \; ; diskutil unmount /volumes/recover

the disk will is mounted, finds and reads the 'SystemVersion.plist', then unmount the disk

the plist text displays in same terminal window.

works here... your mileage may vary

oops. left the 'y' of the 'diskutil unmount' path...

diskutil mount [[disk Identifier]]; find /volumes/recovery -type f -name SystemVersion.plist -exec cat \{\} \; ; diskutil unmount /volumes/recovery

would be a good idea to run... diskutil unmount /volumes/recovery

to make sure it's unmounted

at risk of sounding like a dog with a bone out to beat a dead horse...

i just duplicated the bug!

it is (or was) issue with the catalina installer.

using an archived version of the catalina installer app, I launched the app from mojave... installed and transferred data from mojave to the new catalina.

The mojave partition's recovery volume was changed to 10.15.x

on the other hand...

using the update button in mojave's software update prefs button and not transferring data, using the migration assistant app instead, did not change mojave's recovery volume

i beg everyone's indulgence... but something is nagging at me.

up until 6 months ago i was completely offline for more than a decade, happily working on hobby projects on my trusty 20 year old g4.

i've had a lot of catch-up to do since.

to the point:

i can't believe that i'm the first person to identify the source of this, apparently long term, issue.

I can't believe apple didn't know.

IMHO it's sloppy programming... the os installer should clean up after itself and leave the source os partition just as it was before transferring source data.

certainly not what i have come to expect since my first mac... a brand new macintosh SE.

DCS

nope... looks like a scratch reinstall