If you try to install an older Safari extension in modern Mac Safari versions, you will see an error message stating “Safari no longer supports the unsafe extension “Extension name”. You can find newer extensions reviewed by Apple in the App Store or Safari Extensions Gallery.”
This error occurs because the latest versions of Safari in MacOS do not support extensions that do not have a certificate, or are obtained from outside the Mac App Store and Safari Extensions Gallery, as they are considered unsafe. Nonetheless, some advanced users may want to run these ‘unsafe’ Safari extensions anyway.
This tutorial will show you how to bypass the ‘Safari no longer supports unsafe extension’ error in MacOS Mojave 10.14.x and onward.
How to Get Around “Safari no longer supports unsafe extension” Error in Mac OS
- Find the Safari extension you want to run in Safari and rename the file extension to .zip from .safariext, for example from “mailto.safariext” to “mailto.zip”
- Open the zip file with The Unarchiver, you should end up with a folder named “name.safariextension”, for example “mailto.safariextension” (if you end up with .cpgz file, rename the .zip to .xar, for example “mailto.zip” to “mailto.xar” and unzip the .xar file to unpack the .safariextension folder)
- Now open Safari if you have not done so already, enable the Safari Developer menu if you have not done so already by going to Safari menu > Preferences > Advanced > Show ‘Develop’ menu in menu bar
- Pull down the “Develop” menu and choose “Show Extension Builder” then click Continue to run Extension Builder
- Click the plus + button in the lower corner and choose “Add Extension” then navigate to the .safariextension folder you extracted in the second step
- Click on “Run” to run the extension in Safari and authenticate with an admin password
- Success! The ‘unsafe’ extension is now active and running in Safari
You’ll find the “unsafe” extension in the Safari Extensions manager within Safari Preferences, and in the user Safari Extensions folder.
While this trick works for running the ‘unsafe’ Safari extensions with regular Safari as well as Safari Technology Preview, it’s not recommended to do so. Apple is making the decision to vet approved extensions while labeling other extensions as ‘unsafe’ for a reason, including most third party extensions downloaded from GitHub or elsewhere on the web. Only attempt to run unsafe extensions in Safari if you’re an advanced Mac user with thorough understanding of what the extension is doing and why you’re using it, as a nefarious extension could theoretically read personal web use data.
So if you’re an advanced Mac user and you see the “Safari no longer supports the unsafe extension “Extension name”. You can find newer extensions reviewed by Apple in the App Store or Safari Extensions Gallery.” error message dialog window and want to get around it, now you know how to do so.
Oh and if you were wondering, you can use the command line to unzip the file as well, but Archive Utility seems to send the zip file into a cpgz zip unzip loop. Fortunately The Unarchiver is a great archive decompression tool anyway, so it’s a worthwhile addition to the Mac if you don’t have it yet anyway.