The latest Firefox update, Firefox 57, only supports add-ons using the WebExtensions API. This means that many of your favorite add-ons may stop working. These are being called "legacy" add-ons.
Scary, but true. So what's the solution? Get Vivaldi.
By building in native features like tab grouping, screenshot capture and endless UI customization we're putting the control in your hands. Not relying on add-on support is a great way to avoid your workflow becoming "legacy" too.