Millions of Safari users with ad blocking extensions woke up on September 18 to find their ad blockers turned off without warning after Apple's upgrade to Safari 12. Here's what happened and what to do if you're one of them.


Summary

Apple is making big changes to Safari extensions with the release of MacOS 10.14 (Mojave). As a result, many extensions are being automatically disabled after the upgrade to Safari 12. You can turn these extensions back on in Safari > Preferences > Extensions, but this is only a temporary fix. Eventually, you will need to start using native Mac apps instead.


What happened to extensions in Safari 12?

Apple is making a lot of changes with Safari 12 and Mac OS 10.14 (Mojave). Some of the biggest changes affect extensions, particularly ad blockers.


Starting with Safari 12, Apple is deprecating the canLoad API that ad blockers like AdBlock, Adblock Plus, and uBlock Origin have traditionally used. Safari now supports only the Content Blocking API introduced in Safari 9. Any ad blockers that still include the deprecated API are automatically disabled. Affected users are shown a warning like this one the first time they open their browser after upgrading to Safari 12:


AdBlock is turned off: "Safari turned off extensions that slow down web browsing" notice after upgrade to Safari 12


We and other developers have been preparing for this for months. Nearly two weeks ago, we submitted an update that removed that API specifically so our users would not be adversely affected. Apple wasn't able to approve the release in time to avoid the rude awakening that happened when Safari 12 started rolling out.


Fact check: Does AdBlock slow down web browsing in Safari 12? No. It is true that the newer Content Blocking API is faster than the old canLoad API, which has been deprecated in Safari 12. That's one of the reasons Apple wants developers to use the Content Blocking API exclusively. However, AdBlock is just as fast in Safari 12 as it was in Safari 11.


The other change removes support for self-hosted extensions (extensions installed from the developer's website). If you have been upgraded to Safari 12, you can only install extensions from the Safari Extensions Gallery. Users who try to install self-hosted extensions will see this warning: "Safari no longer supports the unsafe extension" and the name of the extension.


What can you do if your extensions were turned off?

You can turn on your disabled extensions in Safari Extensions Preferences. This is a temporary solution, however. Safari extensions are being phased out in favor of native Mac apps, and Apple is closing the Safari Extensions Gallery next year.


If the developer has created a Mac app version, install it from the App Store. Expect that the app may have fewer features than the extension at first. There are significant challenges to converting .safariextz-style extensions to native Mac apps.


Re-enable the AdBlock extension

If you want to keep using our Safari extension, turn it on again like this:

  1. Click OK to dismiss the "Safari turned off extensions that slow down web browsing" warning.
  2. Open Safari > Preferences > Extensions.

    Open Safari > Preferences > Extensions.

  3. Select the check box next to AdBlock in the left column, then select Enable to confirm (Steps 1 and 2 in the illustration below).

    Select AdBlock, then Enable when prompted to re-enable AdBlock after upgrading to Safari 12.



This is what you should see after you re-enable AdBlock:


AdBlock is re-enabled.


Install the new AdBlock for Safari app

Although you will be able to use our AdBlock extension for a while, you will eventually need to switch to our new app. You can start using the new AdBlock for Safari app today!


Related articles:

Is it true AdBlock will stop working after upgrading to Safari 12?

"Safari 12 no longer supports the unsafe extension AdBlock."

What's different after the September AdBlock for Safari update?

What is Safari Content Blocking?

Why do I see two AdBlock buttons in Safari and three AdBlocks in Safari Extensions Preferences?

Getting started with the AdBlock for Safari app

Frequently asked questions about the AdBlock for Safari app