User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:85.0) Gecko/20100101 Thunderbird/85.0

Steps to reproduce:

1. Preferences → General → Default Search Engine → Add from file
2. Picked a file with following contents:

<SearchPlugin xmlns="http://www.mozilla.org/2006/browser/search/">
<ShortName>DuckDuckGo</ShortName>
<Description>DuckDuckGo</Description>
<InputEncoding>UTF-8</InputEncoding>
<Image width="16" height="16">https://duckduckgo.com/favicon.ico</Image>
<Url type="text/html" method="GET" template="https://duckduckgo.com/">
<Param name="q" value="{searchTerms}"/>
</Url>
<SearchForm>https://duckduckgo.com</SearchForm>
</SearchPlugin>

Actual results:

Uncaught (in promise) TypeError: Services.search.addEngine is not a function
addSearchEngine chrome://messenger/content/preferences/general.js:701

Expected results:

The search engine successfully added.

Indeed, it's now addOpenSearchEngine. We nee to port https://hg.mozilla.org/mozilla-central/rev/1e758dd2af5f110d6f491e955237cc174d7ff4f1 - bug 1632448.

With this the example above can be added. It looks like the url must be a data: uri for the image to work though.

Comment on attachment 9199000 [details] [diff] [review]
bug1687585_searchengine.patch

Works.

Pushed by mkmelin@iki.fi:
https://hg.mozilla.org/comm-central/rev/129709c908c4
Port bug 1632448 -Remove now unused confirm and extensionID parameters for nsISearchService.addEngine, and rename it to addOpenSearchEngine- r=TbSync

Comment on attachment 9199000 [details] [diff] [review]
bug1687585_searchengine.patch

[Approval Request Comment]
Catching up with m-c changes. Safe - it's as broken as it can be on beta anyway.

Comment on attachment 9199000 [details] [diff] [review]
bug1687585_searchengine.patch

[Triage Comment]
Small patch, approving for beta.

Thunderbird 86.0b1:
https://hg.mozilla.org/releases/comm-beta/rev/89a07bc66c89