I keeep a file on my system which is essentially an annotated list of links to useful references. Since upgrading to Firefox 135.0, I can no longer open links to these references if they are local documents (links to websites work fine). Attempting to open a local document (usually an .odt file) brings up a window describing the file and offering tp save it, or open it with the system handler. Opening with the system handler produces an error message "unknown error" and suggests trying saving to disk first. Clearly Firefox does not know how to deal with .odt files, and I can find no way of telling it. If I get to Settings - General - Files and Appications and scroll down the Applications window to ODT document, I find it set to "Always Ask". I can change this to "Save File", "Use System Handler (default) or "Other". "Save File" is not what I am trying to do, and the other two options produce the same result as "Always Ask". There seems to be no way of telling Firefox to open .odt files with Writer (or anything else for that matter.) The support page (https://support.mozilla.org/en-US/kb/change-firefox-behavior-when-open-file) suggests that I should have a further option "Use<application name>". But it just does not appear. Anyone any ideas?