Since installing Safari 12, I've been unable to get my extensions working. In particular I have no functioning ad blocker, and the primary extension I use, Pocket, (rally the only reason I use Safari at all) doesn't seem to work. In order to prevent Safari from showing repeated warnings each time I launch it, I've cleared out my extensions and emptied ~/Library/Safari/Extensions/.
How do I get and ad blocker and Pocket working with Safari 12?
Best Answer
The latest Safari update (12.0, Sept 17, 2018) turns off some and and stops supporting other extensions.
I don't see Pocket on Apple's new list of supported Safari Extensions (https://itunes.apple.com/us/story/id1377753262). That might be why Pocket now recommends that Mac users just use their Mac app: https://help.getpocket.com/article/1042-using-pocket-for-safari
Pocket may update their extension such that Apple starts supporting it again. Until then, there might be a javascript bookmark(let) for saving items to Pocket (https://support.apple.com/en-us/HT4550) or a Pocket email address to which you can send items to your account (https://getpocket.com/add/).
Update: Some unsupported extensions work again in Safari 12. E.g.,