I've seen countless threads about this issue in Safari, and the fix almost always comes down to completely reinstalling the Zotero app. However, there's a workaround that has consistently worked for me without needing to do that.
What I've found is that if you enable Safari's Developer menu and allow unsigned extensions, the Zotero Connector suddenly reappears.
Go to Safari > Settings > Advanced Check the box: Show features for web developers A new Developer tab item will appear From there, select: Developer > Allow Unsigned Extensions
After doing this, the Zotero Connector becomes immediately visible and functional again, you don't even need to restart Safari.
I’m not entirely sure whether this triggers a refresh of Safari’s extension loading mechanism or if it's related to how the Zotero extension is signed, but either way, it works.
Important: Only do this if you know what you're doing, and please avoid installing any other unsigned extensions unless you fully trust the source.
the fix almost always comes down to completely reinstalling the Zotero app
Note that we also suggest compressing → deleting → uncompressing as an alternative. I'd recommend that over toggling developer settings for most people.
I’m not entirely sure whether this triggers a refresh of Safari’s extension loading mechanism
It'd be worth checking if it still works after disabling the setting again. That would clarify whether it's triggering a recompute of the signature or just ignoring the error.
In any case, the bug here is related to signature checking, yes, but it's not a problem with Zotero's signature — when it's not working, you can verify the app's signature with codesign and it passes, and of course, if it were a signature problem, compressing and uncompressing the app wouldn't fix it. My guess is that macOS recomputes the signature while Zotero is still in the middle of updating its files, there's a signature mismatch between the app and the plugin, and then it never checks again. I don't know why it happens during Zotero's update process specifically.
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What I've found is that if you enable Safari's Developer menu and allow unsigned extensions, the Zotero Connector suddenly reappears.
Go to Safari > Settings > Advanced
Check the box: Show features for web developers
A new Developer tab item will appear
From there, select: Developer > Allow Unsigned Extensions
After doing this, the Zotero Connector becomes immediately visible and functional again, you don't even need to restart Safari.
I’m not entirely sure whether this triggers a refresh of Safari’s extension loading mechanism or if it's related to how the Zotero extension is signed, but either way, it works.
Important: Only do this if you know what you're doing, and please avoid installing any other unsigned extensions unless you fully trust the source.
In any case, the bug here is related to signature checking, yes, but it's not a problem with Zotero's signature — when it's not working, you can verify the app's signature with codesign and it passes, and of course, if it were a signature problem, compressing and uncompressing the app wouldn't fix it. My guess is that macOS recomputes the signature while Zotero is still in the middle of updating its files, there's a signature mismatch between the app and the plugin, and then it never checks again. I don't know why it happens during Zotero's update process specifically.