Frequently asked questions - Firefox add-on technology is modernizing | How to

Frequently asked questions - Firefox add-on technology is modernizing

What is a legacy extension?

Extensions built using frameworks that are not compatible with Firefox 57 and beyond (such as SDK or XUL) are considered “legacy” extensions.

How can I tell if I have any legacy extensions installed?

To see if you have incompatible extensions installed, go to the Add-on Manager (Tools menu > Add-ons, or type “about:addons” in a new tab. If you have a legacy extension, you will see a note at the top of your screen like this:

Legacy extension warning

Click on the link “Show legacy extensions” to see a list of legacy extensions installed in your browser. Click on “Find a Replacement” next to each legacy extension for a recommended alternative. You can read more about this feature in our blog.

If I see the “legacy” label, does that mean my extension will break when I upgrade to 57+?

Yes, add-ons labled "legacy" will most likely not work when you upgrade. However, the majority of the most popular Firefox extensions are compatible with Firefox 57+. In some cases, developers are working on updating their extensions to be compatible with current versions of Firefox. In these cases, the extension will automatically update when the compatible version becomes available.

If I see the "legacy" label, does that mean my extension is broken?

Yes, extensions labeled "legacy" will not work with Firefox 57. In some cases, developers will need to continue working after the release date on November 14, 2017 to make their extensions compatible. In these cases, the extension will automatically update when the compatible version becomes available.

Can you recommend replacements for my legacy extensions?

Yes! You can browse our featured collection which consists of popularly used extensions or search on addons.mozilla.org (AMO) for compatible extensions.

Alternatively, you may use the extension finder utility to look up the extension you would like to replace and discover recommended replacements.

Yes! Go to the Add-ons Manager (Tools menu > Add-ons, or type about:addons into a new tab) and select Legacy Extensions. Click on “Find a Replacement” next to each legacy extension for a recommended alternative. You can read more about this feature in our blog.

We recommend that you search for compatible extensions on addons.mozilla.org (AMO) or look through the featured extensions collection.

Alternatively, you may use the extension finder utility to look up the extension you would like to replace and discover recommended replacements.

There aren’t any recommended replacements for one of my legacy extensions. What now?

If you don’t find a suitable replacement, please head over to our forum to ask the community for suggestions.

How can I find extensions that are compatible with Firefox 57 and beyond?

You can search addons.mozilla.org for compatible extensions. The featured extensions collection also includes great extensions that will be compatible beyond Firefox 57.

When will Firefox ESR stop supporting legacy extensions?

Firefox Extended Support Release (ESR) version 52 is the last version that will support legacy extensions. ESR 52 will no longer be supported on September 5, 2018.

In October 2018, all legacy add-ons will be disabled on addons.mozilla.org (AMO). Once this happens, users will no longer be able to find legacy add-ons on AMO.

If you decide to run unsupported releases to use legacy add-ons, this will make you vulnerable to security weaknesses and we strongly do not recommend that they be used.

Will my themes break with Firefox 57?

If you are using a Lightweight Theme, you should not experience any disruption. If you are using a Complete Theme, it will be disabled starting with Firefox 57 and will no longer work. If you use a dark complete theme, the Dark Theme option in the Add-on Manager might be a good option for you. Go to the Themes tab in about:addons and give it a try.

What happened to my complete theme?

Complete themes do not work with Firefox 57+ and are disabled. If you use a dark complete theme, the Dark Theme option in the Add-on Manager might be a good option for you. Go to the Themes tab in about:addons and give it a try. We are making improvements to themes in the coming months, so look for themes with additional functionality beyond an image overlay in future releases.

What happened to my Flash-related add-on?

Starting with the Firefox 55 release, Adobe Flash does not run by default as Click-to-run Flash is built into the browser. You can chose how you want Flash to behave on certain sites or all sites.

Some of the most popular Flash extensions were providing this capability before it became part of the browser. Since these extensions are now obsolete, they will likely no longer be supported by developers and will no longer work.

In some cases, we have WebExtension APIs for additional Flash capabilities (like Flash LSO deletion) and we anticipate add-ons will leverage more Flash capabilities over time and as we work together to discover what is needed to create feature parity.

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// These fine people helped write this article:Tonnes, Michele Rodaro, Andrew, Joni, Caitlin Neiman. You can help too - find out how.

Last Update: 2018-08-16

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