Lots of discussion in #catalina on the MacAdmins Slack on how to disable the above prompt. Turns out even though Catalina isn't a traditional software update, it does still exist as a software update catalog entry and can be ignored in the same way. Run this command to ignore on a single machine...
sudo softwareupdate --ignore "macOS Catalina"
The Catalina banner in Software Update should disappear almost immediately. To send that out to your entire fleet with Jamf Pro, create a new policy with Files and Processes. Under execute command add that command. Scope to whichever Macs you don't want to be prompted. Problem solved! Thanks to folks on MacAdmins Slack for working through this.
To undo what you just did and remove ignored software update entries run...
sudo softwareupdate --reset-ignored
To collect inventory information on what Macs have this ignore software update in place I have an EA. Tested on High Sierra, Mojave, and Catalina. Returns a list of ignored software updates added with the --ignore command. Useful to run advanced searches or smart groups against as needed.
https://github.com/nstrauss/jamf-extension-attributes/blob/master/ignored_softwareupdates.py
@jtrant I think unfortunately that's the expected behaviour from now on (that is after 2020-003 for Mojave is installed)
@carlo.anselmi yes, but it's not supposed to be an issue until macOS 10.16. Dropping the same change in behavior into Mojave (and High Sierra) with zero notice is not cool.
I've already had our Service Desk send me 5 emails from users asking if they can now upgrade.
We are seeing this as well. We also have a policy to restrict the install, but that is not working, either - we have had at least six successful attempts to install even with "Install macOS Catalina.app" in Restricted Software. Is anyone else seeing that issue?
@elsmith have you considered running 'jamf manage' on your clients using a Policy with the "Files & Processes" payload? The old blacklist.xml file is gone and I'm not sure if there is a way to ensure devices have the correct Restricted Software records, but the above should at least get the list updated on your clients.
I have not seen any erroneous upgrades to Catalina, but I am concerned that Restricted Software is now the only thing stopping them. Users can also get crafty and rename the installer, bypassing the restriction.
@jtrant I'm not sure what you mean - how would I do that? (the policy with the "files & processes" payload)
@elsmith you would just insert a jamf manage in that payload to hopefully update their restricted software list, they are saying.
@guidotti @jtrant gotcha!! LOL Thank you!
I just deployed the 10.15.5 update to a test machine, and it renamed the Computer Name to MacBook Pro. Anyone else seeing this happen on any machines?
We have not seen that but all of ours that have updated have been user installs from System Preferences / Software Update.
Ignoring software updates is deprecated.
The ability to ignore individual updates will be removed in a future release of macOS.
I find it highly objectionable that Apple is twisting our users' arms here at least once per day to upgrade to Catalina, which breaks a number of software packages and printer drivers and is still, IMHO, not as stable as High Sierra and Mojave. Next they'll be allowing users to update without an admin password. At one point, this "ignore" thing would make Catalina disappear from the Software Update preference pane. Now it is there all the time.
@Jason33 Yes, was just testing a brand new 10.15 2020 macbook pro and this happened to me as well upon the first update. Then I found this... https://mrmacintosh.com/10-15-4-supplemental-update-resets-computername-hostname-to-default/ Seems to be an Apple issue that was not fixed in the latest update.
The ability to ignore updates has not yet been removed, but Catalina is no longer considered an update (nor does it appear in the SWU catalog) so there is no way to ignore it at this point.
@elsmith @jtrant Our restriction also failed to stop the post macOS security update 2020-03 triggered Catalina upgrades, this was remedied by adding the ".app" suffix to the process name in the restriction. Previously it read "install macOS Catalina" now it says "install macOS Catalina.app" and is working again. Hope this helps.
hi all - has anyone seen this issue re-appear. I have been successfully able to block Catalina appearing on the fleet (running Mojave) using for the last 10 or so months using the the softwareupdate --ignore with "macOS Catalina" and "macOS Catalina 10.15" included in the exclusions.
After the recent "Security Update 2020-003 10.14.6" has been applied, the macOS Catalina 10.15.5 is now appearing in software update with the annoying red (1) appearing. I have catalina installer blocked with restricted software, so ultimately it will be blocked from running (unless users rename the installer) but somehow Apple have changed something so these ignore entries no longer work. Any one come across this, and worked out how to resolve - additional entry in ---ignore list perhaps? I have tried adding "macOS Catalina 10.15.5" but didnt work 
. thx all
Hi @RJH
Same Here, the last sec update breaks the "softwareupdate ignore" setting.
It has been confirmed, using the softwareupdate --ignore is no longer a method that can be used to block Catalina.
see Apple Support Article here.
"Major new releases of macOS are no longer hidden when using the softwareupdate(8) command with the --ignore flag
This change also affects macOS Mojave and macOS High Sierra after installing Security Update 2020-003."
According the linked article (thank you, btw @RJH ), Apple went back and allowed major OS updates to be hidden by the softwareupdate(8) --ignore flag with 15.6
@rmckellar Thats fantastic news - thanks for bringing that to my/our attention!. 10.15.6 was not out at the time of my original post, but Apple have clearly listened and back-pedalled on this change, both for the Catalina and I also note, for Mojave and High Sierra with the 2020-004 Security update applied.
I note that there is a requirement that the macOS device must be "managed", via Apple Business mgr/School mgr or user-approved MDM, which is a fair and reasonable caveat ie. if its managed, we will allow the devices upgrades to major releases be "managed" by Admins etc.. Relieved to see that common sense has prevailed! :)
@RJH I have a test device on macOS Mojave 10.14.6 with 2020-004 Security update applied (18G6020) and user-approved MDM. I ran the softwareupdate --ignore "macOS Catalina" and softwareupdate --ignore "macOS Catalina 10.15.6 Update" from Jamf and macOS Catalina 10.15.6 is still showing in Software updates. In terminal, I only see "macOS Catalina 10.15.6 Update" in the list of ignored updates and I still see the "Ignoring software updates is deprecated" message.
Am I missing something?
@pabohr I think my/our celebrations were a bit premature. I also see the the deprecated message, although with the correct exclusion in place ie. Catalina/10.15 etc. I now see an update pending, but the description is not showing correctly.
Either way - the update is then available to install for a user, which is not the desired outcome.
Still investigating and completing further testing. Let me know if this is also the behaviour you are seeing also.
@RJH I opened a ticket with Apple support for this issue and here is their answer:
*There is an issue we are actively tracking on this. For a comprehensive answer I’m going to be thorough.
On 10.14.6 with the Security Update 2020-004 systems the current expected behavior is:
softwareupdate —ignore can be used to prevent the macOS 10.15 installer from appearing in System Preferences > Software Update
This requires either User Approved MDM (UAMDM) enrollment, or enrollment through DEP (is in Apple Business Manager)
However, currently only Mac hardware enrolled in Apple Business Manager, and thus DEP are correctly respecting softwareupdate —ignore. UAMDM devices do not. Product Engineering is investigating this issue.*
@pabohr thanks for the update. For the environment I work in all the Macs are UAMDM, so this is at least confirmation of the issue, and behaviour we are seeing. I'd be interested to hear back if you get an update from Apple as to perm fix/timelines.
