10.15.3 Combo & Security Updates are not Creating Backup Snapshots

The 10.15.3 Combo & Security Update Automatic Backup Snapshots are no Longer Created.

UPDATE: 5/15/20 – A few questions came up on MacAdmins Slack about the current state of Automatic Snapshots today. To clarify, the following is now true.

• Automatic Update Snapshots are no longer automatically created during the 10.15.3+ Combo but ARE for 10.14 & 10.13 Security Updates
• The 10.15.3+ Combo Update REMOVES previous manual localsnapshots.
• 10.14 & 10.13 Security Updates do NOT remove previous manual snapshots.
• Automatic Snapshots were never taken during an OS Upgrade.

UPDATE: 4/24/20 – Apple has removed the “Restore from snapshot” feature description from apple.com/macos/catalina/features! This means that the feature is no longer available in Catalina. I really hope Apple can fix this.

The APFS Update Automatic Snapshot was a new option offered when Apple released APFS in macOS 10.13 High Sierra. If you were worried about something going wrong after installing a macOS Combo or Security update, you could always fall back to a backup taken right before the update. The process was automatic and was performed by the Combo Update and Security Update Installer. To restore, all you needed to do is, boot to the recovery partition and restore to a tmutil localsnapshot / right before the update.

NOTE: you only have 24 hours to restore or the snapshot is automatically deleted.

Apple explains how this works below.

Automatic Update Backup Snapshots are no Longer Working.

Something happened in the latest set of Apple updates released on January 28th. The Automatic Backup Snapshots are no longer working!!! At first, I thought it only happened on the 10.15.3 Combo update. I then checked the 2020-001 Security Update on High Sierra and it’s not working either!

I found this out while I was writing another article on Catalina Logs. I built a 10.15.2 device and updated it to 10.15.3. I booted to recovery to restore the from the automatic snapshot only to find that it was missing!

Manual tmutil localsnapshots are deleted during the 10.15.3 Update installation!

Ok, what would happen if I created a manual snapshot before the update? If the automatic snapshot is not working, I could get by with just creating one right before I install the 10.15.3 combo update.

After installing the 10.15.3 Combo Update, I booted back into Recovery only to find that the manual tmutil localsnapshot / that I created was gone!!!

What should happen after the update.

Below is what you should see if you booted to recovery after a combo or security update. The below example is a backup snapshot taken by the 10.14.2 Combo Update.

Let’s take a look at the logs

What do the logs say? Well first I would like to see what a successful snapshot says. Searching the install.log, I found exactly what I was looking for.

Let’s take a closer look to see what’s happening during the 10.15.3 combo update install. Looking at the install.log again, I found this entry.

There it is, the Installer is purging available snapshots on /Volumes/Macintosh HD. The 10.15.3 install.log does not contain any of the log items like the one from 10.14.

The good news is that the (2020-001) 10.14 and 10.13 Security Update installers do NOT purge your manual tmutil localsnapshots.

What’s going on, is this a bug?

I am not totally sure what’s going on here, if I had to guess this a bug. I wanted to let you know about this. The last thing you want to do is rely on that automatic backup snapshot only to find out it was never created.

Either way, please let Apple know about this!

If you have any questions or comments please Contact Me or leave a note below. Thanks!