“Update” disk appeared after Tahoe update

If your macOS update completed successfully and seems to be running well, try “Delete an APFS volume“ as described here.

Add, delete, or erase APFS volumes in Disk Utility on Mac - Apple Support

pumbers wrote:

Nope, none of that installed. I did find, however, that the Finder sidebar setting for viewing hard disks had been turned on. This is something I didn't do, and I've never seen it happen in previous updates.

Turning it off makes the drive go away, so as long as that doesn't set me up for the failure of a future update, I'm happy.

You can remove items from the Finder's sidebar so you can retain any other mounted volumes you wish to keep on the Finder's sidebar. You can right-click or Control-click on the item on the Finder's sidebar and select "Remove from sidebar".

Having the normally hidden "Update" volume visible won't hurt anything, it is just annoying.

pumbers wrote:

A few days ago, I upgraded my MacBook Pro M3 to Tahoe 26.5.2. I noticed today that I have a new disk mounted in Finder called “update”. I’ve tried ejecting it, even after multiple restarts, but I just get multiple messages telling me a process is using the disk. I’ve not noticed any other issues with the machine.

I’ve searched online and found a lot of conflicting reports. It appears it’s a temporary disk created during the update process that it failed to remove when complete. Some reports say to just leave it, some say it’s ok to force eject it, some say it means I should reinstall the OS from scratch.

Can anyone please clarify what I need to do here, preferably without screwing up the machine? Can I just leave the drive there? Will it cause future updates to fail? Can I force eject it?

You can safely ignore it. I have heard of no subsequent consequences.

I've seen report of this bug before—

To be proactive you can file a bug report / submit your feedback here: Feedback - macOS - Apple

If you are insistent— you can reinstall the macOS on top of your existing macOS

How to reinstall macOS - Apple Support

pumbers wrote:

The update appeared to complete normally, and except for this phantom drive showing up I've not noticed any problems. I've checked Disk Utility and there is no corresponding APFS volume showing there.

https://discussions.apple.com/content/attachment/500dd6d2-ef52-41e4-90eb-cc3e0b9ab26b

The "Update" volume is part of macOS which is usually hidden from view. For some unknown reason some people end up seeing it.

Since I've never seen any of the regular forum contributors from seeing the "Update" volume, it is my guess that users have some sort of system modification which has caused this hidden APFS volume to appear. Anti-virus software, cleaning/optimizer apps, and third party security software would be the first items which would be most likely to cause unexpected behavior because they interfere with the normal operation of macOS. You can try uninstalling those apps by following their developer's instructions, but that may not revert any system modifications they may have created.