User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:58.0) Gecko/20100101 Firefox/58.0 Build ID: 20171218174357 Steps to reproduce: I installed the "Google Search for Thunderbird" add-on, I copied the XML file manually (see https://support.mozilla.org/en-US/kb/add-search-engine-open-search) and I tried this XML file for DuckDuckGo (https://duckduckgo.com/opensearch.xml) Actual results: No new search engines were added in thunderbird Expected results: "Google" and "DuckDuckGo" should have appeared on the list of availabe search engines ( Options ->General -> Default Search Engine) https://support.mozilla.org/en-US/kb/open-search

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.0 Application Build ID: 20171209081708 I can confirm this bug on my system. And according to this https://support.mozilla.org/en-US/questions/1196683 Mozilla Support Forum question the workaround is to move/rename/delete the file `search.json.mozlz4` from Thunderbird profile directory.

Sorry but this workaround isn´t working (anymore).

(In reply to Thomas Faßnacht from comment #2) > Sorry but this workaround isn´t working (anymore). On Debian Stretch I can confirm that it's working. But perhaps for latest TB it doesn't.

Removal of that file is also mentioned in bug 1427167. So, Matt, is this still working or not?

Please read bug 1427167 comment #2. Apparently dropping in XML files is not supported any more.

Clearly it worked for Avinash. I can reproduce his results the release versions to 54.5.2. on Windows. So I would say in the release 32bit version it works. In Daily it does not work. I tried both the 32 and 64 bit versions and neither generated a correct search.json.mozlz4. I have saved the files, if anyone needs them. But I guess we have a regression between 52.4.2 and Daily. Version 59.0a1 Build ID 20171228030203 I do not know if it is related, but the add-on search does not appear to be working in Daily either. I assume it functions on opensearch.

More info in bug 1427167. Add-on search is different and might not work while TB is moving to its own add-on site.

It would be nice to have this function properly. Using TB 52.6.0 (32-bit) I also want to use DDG. Tried the process above - Shutting down TB, locating the profile folder, creating a searchengine folder, adding opensearch.xml. restarting TB. did not work. Tried locating search.json.mozlz4 and renaming by adding .old to the end. The json file was not in the profile so did not work either.

We're working on it in bug 1427317.