The curious case of the disappearing search engine add-on

super70s's Avatar


06 Mar, 2019 03:58 PM happens to be my favorite search engine and, after installing its add-on, I use it as a default in TFF. The problem is every few weeks it not only stops being the default search engine, but the add-on disappears and I have to re-install it. This doesn't seem to be the fault of the add-on because I've installed several different Startpage add-ons and they all wind up going away after a while.

Is this some kind of bug with Mozilla and not TFF's fault?

  1. 1 Posted by KGB on 24 Mar, 2019 08:01 PM

    KGB's Avatar

    My addons work fine and appear to be stable. However the top line of the addon box -search for addons- is missing.

  2. 2 Posted by Raphaël Guay on 02 Apr, 2019 05:15 AM

    Raphaël Guay's Avatar

    I have come up with a plausible theory to explain why people still get their search bar add-on reset to factory defaults (And I do have steps to reproduce reliably, at least for me).

    STRs first:

    (Recommended) Use a slow machine (both an 1.33ghz 12" iBook at reduced perf setting or a 7400-based G4 tower facilitate me reproducing it every time)

    1- Backup your current (user-set search engines) search.json file to avoid it being clobbered;

    2- start up TenFourFox;

    3- Right when the first window shows up, immediately click the search bar and input something (1 character should do). Do it as fast as possible, don't wait until it's responsive;

    Once the search drop-down menu opens up the factory default search engines should be there instead of your user-set ones.

    To back this not being data corruption, I can:

    4- write-protect my (user-set) search.json inside my profile via finder > get info;

    5- repeat steps 2 and 3, observe the default search engines showing up again in search bar menu;

    6- quit TFx, reopen it (wait until it's fully responsive);

    The search engines should be back to user-set ones since search.json couldn't be overwritten.

    I can reproduce this with a brand new profile (except search engines of course). My default first page is usually set to blank.

    So that suggests when I do this, parts of the user profile are not loaded completely and the browser assumes search.json is corrupted since it's not ready yet. So I can't seem to find this reported in Fx esr45 because faster browser load times likely wallpaper this?

    Can anyone try this to let me know if I'm the only one able to reproduce this? Thanks!

  3. Support Staff 3 Posted by Chris (chtrusch... on 05 Apr, 2019 07:48 PM

    Chris (chtrusch)'s Avatar

    I was able to reproduce this on my Pismo 400 MHz G3.

    Also see here:

    Maybe removing the LZ4 method from search.json is only part of the solution, resp. the actual problem isn't LZ4 but loading speed.

  4. Support Staff 4 Posted by Cameron Kaiser on 07 Apr, 2019 07:46 PM

    Cameron Kaiser's Avatar

    A speculative fix might be to force the load to complete but I have to investigate how that gets kicked off. There could well be a race condition here.

  5. 5 Posted by super70s on 17 May, 2019 10:46 AM

    super70s's Avatar

    What's going on with, the Startpage search add-on just disappeared again and now I'm getting a "Your version of Firefox does not support search plugins" when I try to reinstall it. Even after I change the user agent string to Firefox 60ESR.

    I wish they wouldn't try to be 2 cute by 1/2 with this stuff.

Reply to this discussion

Internal reply

Formatting help / Preview (switch to plain text) No formatting (switch to Markdown)

Attaching KB article:


Attached Files

You can attach files up to 10MB

If you don't have an account yet, we need to confirm you're human and not a machine trying to post spam.

Keyboard shortcuts


? Show this help
ESC Blurs the current field

Comment Form

r Focus the comment reply box
^ + ↩ Submit the comment

You can use Command ⌘ instead of Control ^ on Mac