The only downside is that it sends notifications that cannot be turned off without also turning features off.

Please make it possible to toggle notifications on or off.

Its good. However if the web page is not found in web.archive.org also, then it repeatedly tries to load the same archive page again and again in infinite loop.

Good extension, but one alternative may prove more useful for you.

If you primarily use the archive.org Wayback Machine, I would probably recommend their extension over this, as it can automatically fetch pages from it that receive 404 errors, which provides a seamless experience. (A feature this app may consider adding, along a configurable default source source.)

However, this extension is useful in that in addition to the Wayback Machine, it also provides access to archive.is and Google WebCache.

If "Automatic page retrieval for "Problem loading Page"" is activated, the addon will try to open about:newtab on archive.org. This shouldn't be happening.

I really like that Get Archive is not only using the WayBackMachine, but also archive.is and others.

Got one beef so far, though: would be awesome if there was an option to disable notifications. Whenever I reach a 404 or something similar, the add-on in Firefox on macOS spawns a notification in Notification Center.