Can't enable safari extensions

Yes. Quit any apps that put overlays on screen, such as F.lux or any other apps that augment system wide display. That, or restart in Safe Mode (with shift down) and make your changes in the Safari Preferences.

Boot into Safe Mode (Use Safe Mode to isoloate issues with your Mac and Playing Safe: what does Safe Mode do?) and try activating the extensions from there. Then reboot normally and check.

NOTE: Safe Mode boot can take up to 10 minutes as it's doing some system cache cleaning, volume verifying and directory repairing. 

Do you have a second user account on your Mac that does not have any of the "extras" added to it, i.e. LittleSnitch, HazeOver, etc? If not then create a new user account, non-admin, and see if you can add extensions to Safari to it. This will let us know if there are any 3rd party software that's interfering with the process.

Can't believe that this worked, but it did. The problem came back for me at some point. After opening Preferences, I went to Extensions, clicked the checkbox to activate one, nothing happened, I dragged the window to the opposite side of the screen from where the dock is, and then I clicked, and the checkbox worked.

That's so dumb, haha, but it worked.

This issue seems like a MacOS 10.15.3 Safari bug according to a start of a good technical analysis of the issue here https://lapcatsoftware.com/articles/enable-extensions.html - it describes the "easier" possible workaround steps (moving Preferences to a different part of the screen, switching Safari preferences panes & moving, and temp disabling Apps in the Accessibility System Preferences).

These workarounds didn't work for me. I ended up frustrated with the lack of my regular browsing experience with Adblock & 1Password 7.4.3.

So went to the more extreme workaround:

I re-installed MacOS 10.15.1, successfully re-enabled my Safari extensions (ie clicking the checkbox to enable the extension worked as expected), then re-installed MacOS 10.15.4 - now, Safari extensions are still enabled and everything working as expected (and I'll not disable them at least until the bug is fixed).

Notes: I happened to have 10.15.1 previously saved so I used that to boot from an external drive to re-install over existing install, without formatting so all my data, apps, etc & extensions are still there.

Wow, I solved this by moving the Preferences window away from the dock! All of a sudden I could select the checkboxes again!

The "Window is occluded" message I saw in the Console, when trying to enable an extension, led me to close any apps that use overlays on screen, such as software brightness apps (QuickShade, Nocturnal), night mode type apps (Flux, Nocturnal), rounded corner adder apps (Displaperture). 

Quitting / killing those apps (or not starting them) had resolved the issue for me, and allowed me to enable Safari Extensions again.

Tried all of the above w/o success. Finallly, just quit everything else that was running, in this case, disk utility, sonos controller, wipr (which I was trying to install), leaving only safari and whatever background processes were running and the check boxes worked for 1Password and Wipr (my only extensions). Hope this helps.

 I might have found one — can you go to Safari > Preferences > Extensions, then navigate to a different pane (e.g., Advanced), and then back to Extensions? With any luck, your checkboxes might be enable-able now. Please let me know. 🙂 This worked for me.

I never booted the Mac or go into any safe mood or anything crazy like that.

Personally I've solved this a couple of hours ago booting my MacBook in Safe Mode, enabling the extension in Safari and rebooting the machine.

Now all the extensions works as intended.

Good luck!

dcdunk wrote:

javajunkie wrote:

Empty Caches seemed to do the trick. I was able to activate the extensions.

bravo dominic23—maybe if we are lucky the OP dcdunk will let us now if this resolved their issue...😉

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I thought today's update would have fixed this, but it didn't. None of the other solutions in this thread work for me. Nevertheless, I am using the Safari Technology Preview instead and it works fine that way.

Download and run Etrecheck. Etrecheck is a diagnostic tool that was developed by one of the most respected users here in the ASC and recommended by Apple Support  to provide a snapshot of the system and help identify the more obvious culprits that can adversely affect a Mac's performance.

Copy the report

and use the Add Text button to include the report in your reply. How to use the Add Text Feature When Posting Large Amounts of Text, i.e. an Etrecheck Report

IMPORTANT:

Before running Etrecheck assign Full Disk Access to Etrecheck in the app's Privacy preference pane so that it can get additional information from the Console and log files for the report:

ALSO IMPORTANT:

Then we can examine the report and see if we can determine the root of the problem.

I stumbled upon the fix by accident.

I tried all the fixes mentioned here and nothing worked for me. I even reinstalled my OS and tried enabling the extensions in safe mode. Didn't work for me. Currently i am using mac os 10.15.4.

I had installed adblock pro and could not enable it. After all my efforts I deleted adblock pro from the launchpad by dragging it to the recycle bin. On opening the safari extensions i could see a blank image of adblock pro in the extensions. On clicking it it got enabled. I reinstalled adblock pro and checked it. I was amazed that it stayed enabled and worked like a charm in youtube. ( Had never expected this)

Hope this works for you also. Thank you.

THIS LITERALLY WORKED

The only thing that worked for me: drag the installation//app to the bin from the launchpad then went back onto safari>preferences>extensions, tried ticking the box again and it worked!!!! Then download the installation//app again (I had to recheck the box AFTER this also but this time it worked XD!!) and carry on browsing!

^This is on my Mac btw