title: Safari says "No Extensions", can't add any extensions
body: <p>Safari extension window says "No Extension". Can't add any extension as well. I am running macOS Mojave 10.14.5 (no beta).</p>
  
  <p>Following did not help : Disable/Enable Extensions from Develop menu, restarting safari, restarting mac, removing ~/Library/Preferences/com.apple.Safari.SandboxBroker.plist</p>
  
  <p>This might have happened after I installed a profile (.pkg file) to receive beta OS update. But I never installed the beta.</p>
  
  <p>How do I add extensions to Safari ? Any help ?</p>
  
  <p><a href="https://i.stack.imgur.com/gweb0.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/gweb0.png" alt="enter image description here"></a></p>