Yesterday, after my mint 20.3 system updated Thunderbird, it stopped connecting. I purged Thunderbird and deleted the Thunderbird folders from /usr/cache and home/chris directories (can't seem to delete the archive folders). I've tried reinstalling multiple times and get the above error trying to set up my Yahoo mail account. I've tried leaving the "@yahoo.com" on and off my username, tried all the authentication methods. My server settings are correct. I installed Thunderbird on my Macbook yesterday perfectly doing nothing different. Starting in safe mode in terminal gives: [ImapModuleLoader] Using nsImapService.cpp [NntpModuleLoader] Using NntpService.jsm [Pop3ModuleLoader] Using Pop3Service.jsm ATTENTION: default value of option mesa_glthread overridden by environment. ATTENTION: default value of option mesa_glthread overridden by environment. ATTENTION: default value of option mesa_glthread overridden by environment. ATTENTION: default value of option mesa_glthread overridden by environment. [calBackendLoader] Using Thunderbird's ical.js backend console.debug: "Found 0 public keys and 0 secret keys (0 protected, 0 unprotected)" console.debug: "Successfully loaded optional OpenPGP library libgpgme.so.11 from system's standard library locations" console.debug: "gpgme version: 1.13.1-unknown" console.warn: services.settings: Failed to load last_modified.json: TypeError: NetworkError when attempting to fetch resource. console.debug: "Trying to load /usr/lib/thunderbird/libotr.so" console.debug: "Trying to load libotr.so from system's standard library locations" console.debug: "Trying to load libotr.so.5 from system's standard library locations" console.debug: "Trying to load libotr.so from system's standard library locations" console.log: (new Error("Cannot load required OTR library", "resource:///modules/OTRLib.jsm", 109)) console.error: Region.jsm: "Error fetching region" (new TypeError("NetworkError when attempting to fetch resource.", "")) console.error: Region.jsm: "Failed to fetch region" (new Error("NO_RESULT", "resource://gre/modules/Region.jsm", 419)) console.error: Region.jsm: "Error fetching region" (new TypeError("NetworkError when attempting to fetch resource.", "")) console.error: Region.jsm: "Failed to fetch region" (new Error("NO_RESULT", "resource://gre/modules/Region.jsm", 419))