They force you to install Yandex Browser instead of Firefox, probably. Silly move.

Btw, Google Chrome still supports Yandex as a search engine.

Probably the only solution to solve the problem is deleting Firefox and install the browser which supports the desired search engine.

the solution:

Open yandex.ru -> in address bar, do a right mouse click and choose "Add Yandex" -> go to search engines settings and choose yandex as default.

Hi

Yandex and Mail.ru have been removed as optional search providers in the drop-down search menu in Firefox. You can update and/or add search engines at any time in Settings. Click the Menu button, select Settings and click Search.

Also https://mycroftproject.com/search-engines.html?name=yandex

They force you to install Yandex Browser instead of Firefox, probably. Silly move. Btw, Google Chrome still supports Yandex as a search engine. Probably the only solution to solve the problem is deleting Firefox and install the browser which supports the desired search engine.

No this is not it, and Firefox web browser still allows the Yandex search to be installed if the user wants it and there is no need to install another web browser just to use Yandex search engine or the Yandex site.

Also you do not need to delete/uninstall Firefox in order to use another web browser.

@James

Ok, Николай's solution works. But i can't catch the idea what happened previously.

Firefox explicitly shown the message below toolbar like "Firefox doesn't support Yandex anymore, your search engine was changed to Google". Then Yandex on its pages added a popup banner for Firefox users with suggestion to install Yandex Browser against blocked by Firefox default search engine preference.

Glad to hear that Yandex is still available as option. Yandex has a rather better search quality in .ru internet segment. Btw, I often use Google to search something in English network. If you open search results in Yandex, you can find a small button below the results page sending the query to other different seach engines including Google, that's a nice feature.

Thanks, Firefox.

Was this change forced by the US government? Why did the Yandex search disappear from the list of possible search engines? Why is google/etc are better than Yandex in any regard?