Firefox users who run a recent Nightly version of the web browser may have stumbled upon a puzzling change that Mozilla implemented recently in the development version.
Firefox users who attempt to install a search provider from Mycroft Project, Mozilla AMO, or any other site that supports it, will notice that this is not possible anymore in the most recent Nightly version.
All you had to do previously was click on a search provider to get the “Add Search Engine” prompt to add it to the list of supported search engines.
Selection of a search provider link on a site like Mycroft Project does nothing anymore in Firefox Nightly (currently Firefox 65).
The sites use the method AddSearchProvider() for the functionality; the method is deprecated and support for it will be removed from Firefox.
Mozilla made the change in Firefox Nightly 65 already which is why users of Nightly can’t add search providers anymore using sites and services that make use of the method. The organization did so to collect regressions and plans to disable the functionality in Firefox 66 Stable for all users.
Mozilla explains on the Firefox Site Compatibility blog:
The IE-derived window.external object will remain, but the AddSearchProvider and IsSearchProviderInstalled methods on it will be no-op, simply returning undefined, according to the latest HTML spec. This change has also been made to Firefox 65 Nightly.
While AddSearchProvider could be used to add an OpenSearch plug-in to the browser, IsSearchProviderInstalled was always returning 0 on Firefox.
The change does not impact Firefox’s auto-discovery capabilities; the browser picks up open search engines automatically (provided that they use a specific format) so that users may use these in Firefox or make them the default.
Firefox users may also add any search engine that is picked up by Firefox using the search field in the browser.
A bug on [email protected] highlights the controversial nature of the removal in Firefox. The deprecation breaks Firefox extensions such as Add Custom Search Engine that make use of the feature, sites like MyCroft Project, and also search engines that are available on AMO (Addons Mozilla Org).
The critical nature of the change could lead to a postponing to resolve some of the side-effects of disabling the functionality in the Firefox browser.
Now you: how do you add search engines to Firefox?
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