Hi QuiGonGene,

have a look at this article: Search bar - add, change and manage search engines on Firefox.

Also, here is a list of search tools:

Search Tools
Additionally, here is a page about the Search bar where you will find all information you need:
Search Bar
Finally, have a look here:
Unable to search or add new engines
Shortly,
If the Search Bar no longer works or you can't add new search engines, the problem may be a corrupt "search.sqlite" file. Try the following solution:

• Exit Firefox and go to your Firefox profile folder.
• Delete (or rename) the file "search.sqlite".
• Re-start Firefox to see if it solves your problem.

If the problem is not resolved, exit Firefox again, go back to your Firefox profile folder and delete (or rename) the file "formhistory.sqlite" (also delete "formhistory.sqlite-journal", "formhistory.sqlite.corrupt" and "formhistory.dat", if they exist). This may resolve the issue but will remove all Saved Form data from Firefox.
More information can be found at the articles above.
Hope that helped you!

In order to get that alert you're failing this javascript:

window.external && ("AddSearchProvider" in window.external)

I don't see any extensions that are known to cause problems. You're not posting this from a different machine / setup are you? (If you were on Ubuntu I'd point to https://bugs.launchpad.net/bugs/1069793 ) [Edit to fix link that had bracket included...]

(I'd try safe mode: https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode to eliminate extensions, etc)

Okay, it must be one of my add-ons causing the problem. I put Firefox into safe mode, and I was able to add search engines with no problem at all. I'm not even going to worry about which extension is the problem, because I can just use safe mode if/whenever I want to install more search engines. Thank you! I'm new to Firefox, and would not have known to try safe mode.

I'm having the same problem but on Ubuntu 13.04. The link (https://bugs.launchpad.net/bugs/1069793) provided by Mycroft leads to an Error page saying "This page does not exist..." etc. What solution can I use?

Hi Milind

Did you try Firefox Safe Mode?

Start Firefox in Safe Mode to check if one of the extensions (Firefox/Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Firefox/Tools > Add-ons > Appearance).

• Do NOT click the Reset button on the Safe Mode start window.

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

I've fixed the link (oops)

Disabling 'Unity Desktop Integration' should fix the issue

I started Firefox in Safe Mode and installed the search engines which I wanted from mycroftproject.com. Thanks to cor-el and Mycroft.