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Multi-process Firefox and Add-ons: A Call to Action for Extension Developers

As we mentioned previously, Mozilla will be introducing multiprocess Firefox (e10s) to selected users with the release of Firefox 48. Installations of Firefox that do not have add-ons installed or accessibility features enabled will have multi-process support enabled by default over the next six weeks. We’ll be testing multiprocess Firefox with add-ons in the release channel starting in Firefox 49, with the intent to make it the default for all installations of Firefox in early 2017.

While a number of existing add-ons will work with multiprocess Firefox, some will not work, or will not work well. We’d like add-ons to “just work”, so users will be able to use all their favorite extensions while experiencing the benefits of e10s as it’s rolled out to them. To this end, we have an urgent request for developers of add-ons who have not tested their add-ons for e10s compatibility or switched to WebExtensions already:

Then, take one of the following paths:

  • If your add-on works as expected with e10s, mark it as multi-process compatible and upload the new version to AMO and/or your updateURL
  • If your add-on doesn’t work as expected with e10s, adapt it to work with e10s, mark it as multi-process compatible and upload the new version to AMO and/or your updateURL

Additional information on e10s, add-ons, and WebExtensions are available on a Mozilla Wiki and MDN, and we’re also here to help you make the transition. While it seems far away, 2017 is just a few months away, and we’d ask that you test—and update, if necessary—your add-ons as soon as possible.

8 comments on “Multi-process Firefox and Add-ons: A Call to Action for Extension Developers”

  1. bethov wrote on

    i downloaded firefox 47.0.1 and when i require a site it wont open, that applied for all sites, what i did wrong???

  2. Larry Atkins wrote on

    Hi. I’ve developed 7 extensions, and all are marked multi-process compatible.

    However, I have a question about other developer’s extensions that I’m using. Is there any good way I can check to see if they’re mp-compatible? The last time I looked at the Mozilla home pages of various extensions, there was no such indication, nor is there any indication in about:addons. Is there anything in the pipe to help with this?

    1. Jorge Villalobos wrote on

      The Add-on Compatibility Reporter add-on will expose this information.

      1. Dan wrote on

        Does it? The description on AMO says it’s to allow users to report “this is broken” and doesn’t say anything about exposing failure reports from other people to anyone who has it installed. In addition, I installed it to see what would happen, but it doesn’t appear to do anything except let me report any problems I have.

  3. LosInvalidos wrote on

    1Password Firefox extension broken with e10s enabled:

  4. Em wrote on

    Enormous changes, big troubles, for little gains.

  5. Jeff Kemble wrote on

    iMacros 9.0.3 Update in response to Firefox 48.0 (Multiprocess)
    Error: Accessing content window is not supported in multiprocess Firefox, line 208 (Error code: -991)

    Noticed iMacros 9.0.3 error when calling multiple javascript files by .bat… So we have a .bat file that calls .js files which call .imm (iMacros)… After the first .js file, it locks up with the error mentioned in the title. Now need to go back to iMacros 8.9.7 until this is resolved or until a fix is put into place.

  6. Not Telling wrote on

    I suggest that depending on the add-ons you use to decide whether or not to even update to the new mozilla firefox by clicking the options button in your menu bar’s tools tab, then going to advanced, and then selecting the updates tab on the advanced menu, and setting your firefox updates to check for updates, but let me choose whether to install them.

    that way you can use the old working version of firefox that your add-ons still work on instead of going to the new firefox that can’t run your add-ons.