I just got a new MacBook Air (M5), replacing my old 2011 model. It came with macOS 26.2 pre-installed, but on the first boot, it insisted on self-upgrading to 26.4 (taking several hours, including a 10 GB download) before I could even log in the first time.
I chose to not migrate anything from my old laptop, but instead to manually install the apps I care about. Two of my apps are pretty old and are not signed/notarized:
When I downloaded these and tried to run them, I got the usual Gatekeeper warning. I then went to the System Settings to approve the app and run it anyway. The apps didn’t launch - they icon just bounced in the Dock for a long time and the app never started (and I couldn’t launch anything else until after logging out/in - looks like something in Launch Services got hung up). A power-cycle didn’t help.
Since these apps were very old, I assumed that they were simply not compatible with macOS 26, but when I zipped up the same apps on my other Mac (running macOS 15), where they work, copied over the zip file and extracted the apps, they worked just fine.
So there’s something wonky in Gatekeeper with macOS 26.
I’ll probably run some experiments to see if manually removing the quarantine attribute produces different results, and I’ll re-try this test when the next macOS update is released, but I’m wondering if anybody else has seen this behavior.
BTW, everything else I installed just worked fine:
Interesting. Did you do it from an admin account or from a non-privileged user account?
I was logged in as a non-privileged user. In the past, the system would prompt me for admin credentials as a part of authorizing the app. Maybe that’s where the bug lies.
Thanks. I ran some more tests. Using an admin account, it works as expected - the button in System Settings asks me for password-confirmation, and then removes the quarantine attribute and launches the app.
From a non-admin account, it never asks for the password, and the app doesn’t launch (the icon bounces without end in the Dock). And other apps fail to launch until I force-quit the bouncing icon and log out.
And when logging out, I briefly see a window appear (just before the desktop closes) that looks like it’s asking for an admin password.
If I manually remove the quarantine attribute from the DMG image:
$ xattr -d com.apple.quarantine Puzzles.dmg
And then copy-out the app, it also launches without incident.
So, it would appear that the problem is that with a non-admin account, something in launch-services is deadlocking, preventing me from authenticating the installation. But it works fine from an admin account.
I’ll leave Feedback with Apple about this. Hopefully, they can get it working soon. But if not, I now know of two workarounds (install from Admin or manually remove the quarantine attribute).
there are several ways to fix these apps, YouTube have videos that I tried myself and it works in similar situation. (I am new here so I can’t add links )
I haven’t seen the videos you’re referring to, but I’m sure that they all are going to ask you to do one of the following:
Go to System Settings → Privacy & Security and click the button to approve the app. macOS should then ask for an administrator password. This doesn’t work on 26.4 (at least not for me) if you’re not logged in to an admin account, and is the issue I’m describing.
Move the app to the Applications folder and launch it. This should (usually) be the same as manually approving the app. It didn’t work for me from a non-admin account. I didn’t try it from an admin account.
Right-click on the app and select Open from the popup menu. Then provide an admin password. This feature was removed from the latest versions of macOS.
Disable Gatekeeper. This is not recommended, because it will allow all unsigned apps to run, not just those you explicitly know to be safe.
Manually remove the com.apple.quarantine extended attribute. This worked for me and should, in general work.
Use a third-party utility, like xattred to remove the quarantine attribute a bit more easily.
It sounds to me as if your system is asking for an admin password, but for some reason the dialog is hidden, perhaps under another window. If it happens again, try using app-exposé, probably in the Finder. See if the dialog is hiding somewhere.
(There are various ways to invoke app-exposé. I think a default is cntl-down arrow.)
I just tried from a non-admin account on my Mac mini. It worked the same way as with an admin account, including getting a prompt for an admin account to allow running the app. This is a Mac mini on 26.4, built from scratch on Seqouia last year and just recently upgraded.
Very interestingly, I installed on another Mac mini I have, recently built from scratch on 26.3.1 and then upgraded to 26.4. The two Mac minis sync their download folders using the app syncthing, both are running standard accounts, and when I installed and then ran Disk Inventory X on the second machine, it wasn’t even prompted - it simply ran. I assume that the approval on one machine somehow synced with the downloaded .dmg file to the other machine.
If you approved the app one computer, and copied it to another, then you should expect it to just work.
The quarantine flag is voluntarily added by apps that perform downloads (typically web browsers). I’ve found that command-line tools (like sftp) don’t add it. It wouldn’t surprise me if a drag/drop from a shared folder doesn’t either.
If you want to force it to ask again, your best bet is to download a fresh copy from the Internet via a web browser. Or use a tool like xattred to manually add a quarantine flag.
One thing to be aware of is that Syncthing can be configured to either sync or ignore extended attributes (such as the quarantine flag). See the options in the lower right:
What is that screen-shot from? It doesn’t look like an Apple dialog.
Either way, it doesn’t affect what I wrote. Apple doesn’t force apps to add a quarantine attribute to downloaded files. It is a recommendation that is done by web browsers and some other apps, but definitely not all.
The screenshot is from Syncthing, which provides a web UI to control its settings. (There are also various native GUIs around, like Synctrain, but @ddmiller didn’t mention one.)
I agree that it doesn’t change anything about what you wrote, which is correct. I wanted to point out a reason why the behavior might differ between two Macs using Syncthing, even if an app was downloaded using a tool that does add the quarantine flag on one of them. It’s not always clear what macOS features depend on certain file attributes / filesystem features; I’ve been surprised by that in the past.
Yep, I use Syncthing installed in ~/bin with a plist file in ~/Library/LaunchAgents to launch it on log in. I’ve been using syncthing for years now. It’s a fantastic app.
