Please post a screenshot of the error. https://support.mozilla.org/kb/how-do-i-create-screenshot-my-problem

'''Christ1''' - I have a screenshot but image upload doesn't appear to be working (I've been waiting for 10 minutes for my 93Kb image to load)

Trying a smaller image...

Is there anything related in the error console (Ctrl-Shift-J)? What is your anti-virus software?

           resource:///chrome/en-US/locale/en-US/calendar/messenger/otr/otrUI.ftl while it's being loaded asynchronously. L10nRegistry.jsm:597:19

I am using Windows Defender for virus protection. I just restarted Thunderbird and the error console shows several lines of errors: 16:54:59.111 Unexpected event profile-after-change URLQueryStrippingListService.jsm:224 16:55:00.171 NetworkError when attempting to fetch resource. RemoteSettingsClient.jsm:413:14 16:55:00.370 [l10nregistry] Attempting to synchronously load file resource:///chrome/en-US/locale/en-US/calendar/messenger/otr/otrUI.ftl while it's being loaded asynchronously. L10nRegistry.jsm:597:19 16:55:00.370 [Exception... "Component returned failure code: 0x80520001 (NS_ERROR_FILE_UNRECOGNIZED_PATH) [nsIXPCComponents_Utils.readUTF8URI]" nsresult: "0x80520001 (NS_ERROR_FILE_UNRECOGNIZED_PATH)" location: "JS frame :: resource://gre/modules/L10nRegistry.jsm :: L10nRegistry.loadSync :: line 692" data: no] L10nRegistry.jsm:692:19 16:55:00.371 Trying to load C:\Program Files (x86)\Mozilla Thunderbird\libotr.dll OTRLib.jsm:64:11 16:55:00.375 Successfully loaded OTR library C:\Program Files (x86)\Mozilla Thunderbird\libotr.dll OTRLib.jsm:72:13 16:55:00.381 Successfully loaded OpenPGP library rnp.dll version 0.15.2+git20210806.dd923a4e.MZLA from C:\Program Files (x86)\Mozilla Thunderbird\rnp.dll RNPLib.jsm:92:15 16:55:00.566 Found 0 public keys and 0 secret keys (0 protected, 0 unprotected) RNPLib.jsm:288:15 16:55:00.678 NetworkError when attempting to fetch resource. IgnoreLists.jsm:90:10 16:55:01.684 Attempt to override an existing message: "font-size-label". 16:55:01.684 Attempt to override an existing message: "window-close-key". 16:55:01.685 Attempt to override an existing message: "startup-label". 16:55:01.685 Attempt to override an existing message: "focus-search-shortcut". 16:55:01.685 Attempt to override an existing message: "close-button". 16:55:01.764 NS_ERROR_NOT_IMPLEMENTED: Component returned failure code: 0x80004001 (NS_ERROR_NOT_IMPLEMENTED) [nsIRequest.name] 4 OAuth2.jsm:171 16:55:02.164 Attempt to override an existing message: "font-size-label". 16:55:02.164 Attempt to override an existing message: "window-close-key". 16:55:02.164 Attempt to override an existing message: "startup-label". 16:55:02.164 Attempt to override an existing message: "focus-search-shortcut". 16:55:02.164 Attempt to override an existing message: "close-button". 16:55:02.364 [Exception... "Component returned failure code: 0x80520001 (NS_ERROR_FILE_UNRECOGNIZED_PATH) [nsIXPCComponents_Utils.readUTF8URI]" nsresult: "0x80520001 (NS_ERROR_FILE_UNRECOGNIZED_PATH)" location: "JS frame :: resource://gre/modules/L10nRegistry.jsm :: L10nRegistry.loadSync :: line 692" data: no] L10nRegistry.jsm:692:19 16:55:02.364 [Exception... "Component returned failure code: 0x80520001 (NS_ERROR_FILE_UNRECOGNIZED_PATH) [nsIXPCComponents_Utils.readUTF8URI]" nsresult: "0x80520001 (NS_ERROR_FILE_UNRECOGNIZED_PATH)" location: "JS frame :: resource://gre/modules/L10nRegistry.jsm :: L10nRegistry.loadSync :: line 692" data: no] L10nRegistry.jsm:692:19 16:55:38.535 TypeError: window is undefined browsing-context.js:1347:7 16:55:59.257 1642092959257 Toolkit.Telemetry ERROR TelemetrySend::_doPing - error making request to https://incoming-telemetry.thunderbird.net/submit/telemetry/71edf4f0-03fe-4953-aa27-e3bb9bda0ead/first-shutdown/Thunderbird/91.4.1/release/20211216022855?v=4: eUnreachable Log.jsm:723 16:55:59.257 1642092959257 Toolkit.Telemetry ERROR TelemetrySend::sendPersistedPings - failed to send ping 71edf4f0-03fe-4953-aa27-e3bb9bda0ead: {"isTrusted":true} Log.jsm:723 16:55:59.279 1642092959279 Toolkit.Telemetry ERROR TelemetrySend::_doPing - error making request to https://incoming-telemetry.thunderbird.net/submit/telemetry/2746998c-06ea-4588-a484-945dbeef945a/main/Thunderbird/91.4.1/release/20211216022855?v=4: eUnreachable Log.jsm:723 16:55:59.279 1642092959279 Toolkit.Telemetry ERROR TelemetrySend::sendPersistedPings - failed to send ping 2746998c-06ea-4588-a484-945dbeef945a: {"isTrusted":true} Log.jsm:723 16:55:59.325 1642092959325 Toolkit.Telemetry ERROR TelemetrySend::_doPing - error making request to https://incoming-telemetry.thunderbird.net/submit/telemetry/f71dcda6-dd5a-484b-bf12-031f1b8df050/health/Thunderbird/91.4.1/release/20211216022855?v=4: eUnreachable Log.jsm:723 16:55:59.325 1642092959325 Toolkit.Telemetry ERROR TelemetrySend::sendPersistedPings - failed to send ping f71dcda6-dd5a-484b-bf12-031f1b8df050: {"isTrusted":true} Log.jsm:723 16:55:59.327 1642092959327 Toolkit.Telemetry ERROR TelemetrySend::_doPing - error making request to https://incoming-telemetry.thunderbird.net/submit/telemetry/8d1ee59e-4df5-4620-a830-05dffbb745ce/health/Thunderbird/91.4.1/release/20211216022855?v=4: eUnreachable Log.jsm:723 16:55:59.327 1642092959327 Toolkit.Telemetry ERROR TelemetrySend::sendPersistedPings - failed to send ping 8d1ee59e-4df5-4620-a830-05dffbb745ce: {"isTrusted":true} Log.jsm:723 16:55:59.360 1642092959360 Toolkit.Telemetry ERROR TelemetrySend::_doPing - error making request to https://incoming-telemetry.thunderbird.net/submit/telemetry/7a002b16-f843-46d5-b637-8f7920a52abb/first-shutdown/Thunderbird/91.4.1/release/20211216022855?v=4: eUnreachable Log.jsm:723 16:55:59.361 1642092959360 Toolkit.Telemetry ERROR TelemetrySend::sendPersistedPings - failed to send ping 7a002b16-f843-46d5-b637-8f7920a52abb: {"isTrusted":true} Log.jsm:723 16:55:59.395 1642092959395 Toolkit.Telemetry WARN TelemetryStorage::_scanArchive - have seen this id before: 00a375ac-abb6-48be-92c3-22447ef37891, overwrite: false 16:55:59.491 1642092959491 Toolkit.Telemetry ERROR TelemetrySend::_doPing - error making request to https://incoming-telemetry.thunderbird.net/submit/telemetry/70d80b1b-85f3-4db6-8ea2-0b6e1d47b71d/main/Thunderbird/91.4.1/release/20211216022855?v=4: eUnreachable Log.jsm:723 16:55:59.492 1642092959492 Toolkit.Telemetry ERROR TelemetrySend::sendPersistedPings - failed to send ping 70d80b1b-85f3-4db6-8ea2-0b6e1d47b71d: {"isTrusted":true} Log.jsm:723 16:55:59.493 1642092959493 Toolkit.Telemetry ERROR TelemetrySend::_doPing - error making request to https://incoming-telemetry.thunderbird.net/submit/telemetry/2abe7afc-9181-45dd-ba52-ca7cff8aac2e/health/Thunderbird/91.4.1/release/20211216022855?v=4: eUnreachable Log.jsm:723 16:55:59.493 1642092959493 Toolkit.Telemetry ERROR TelemetrySend::sendPersistedPings - failed to send ping 2abe7afc-9181-45dd-ba52-ca7cff8aac2e: {"isTrusted":true} Log.jsm:723 16:55:59.494 1642092959494 Toolkit.Telemetry ERROR TelemetrySend::_doPing - error making request to https://incoming-telemetry.thunderbird.net/submit/telemetry/78bac84b-112e-45b5-97c0-44f04e6c8a38/health/Thunderbird/91.4.1/release/20211216022855?v=4: eUnreachable Log.jsm:723 16:55:59.494 1642092959494 Toolkit.Telemetry ERROR TelemetrySend::sendPersistedPings - failed to send ping 78bac84b-112e-45b5-97c0-44f04e6c8a38: {"isTrusted":true} Log.jsm:723 16:55:59.495 1642092959495 Toolkit.Telemetry ERROR TelemetrySend::_doPing - error making request to https://incoming-telemetry.thunderbird.net/submit/telemetry/21e85cf7-e82f-47d2-b7eb-f627cf7daf09/health/Thunderbird/91.4.1/release/20211216022855?v=4: eUnreachable Log.jsm:723 16:55:59.495 1642092959495 Toolkit.Telemetry ERROR TelemetrySend::sendPersistedPings - failed to send ping 21e85cf7-e82f-47d2-b7eb-f627cf7daf09: {"isTrusted":true} Log.jsm:723 16:55:59.496 1642092959496 Toolkit.Telemetry ERROR TelemetrySend::_doPing - error making request to https://incoming-telemetry.thunderbird.net/submit/telemetry/7a421f49-237f-4b78-9542-49964ae06173/first-shutdown/Thunderbird/91.4.1/release/20211216022855?v=4: eUnreachable Log.jsm:723 16:55:59.496 1642092959496 Toolkit.Telemetry ERROR TelemetrySend::sendPersistedPings - failed to send ping 7a421f49-237f-4b78-9542-49964ae06173: {"isTrusted":true} Log.jsm:723 16:57:59.580 1642093079580 Toolkit.Telemetry ERROR TelemetrySend::_doPing - error making request to https://incoming-telemetry.thunderbird.net/submit/telemetry/8d1ee59e-4df5-4620-a830-05dffbb745ce/health/Thunderbird/91.4.1/release/20211216022855?v=4: eUnreachable Log.jsm:723 16:57:59.580 1642093079580 Toolkit.Telemetry ERROR TelemetrySend::sendPersistedPings - failed to send ping 8d1ee59e-4df5-4620-a830-05dffbb745ce: {"isTrusted":true} Log.jsm:723 16:57:59.708 1642093079708 Toolkit.Telemetry ERROR TelemetrySend::_doPing - error making request to https://incoming-telemetry.thunderbird.net/submit/telemetry/00a375ac-abb6-48be-92c3-22447ef37891/health/Thunderbird/91.4.1/release/20211216022855?v=4: eUnreachable Log.jsm:723 16:57:59.710 1642093079710 Toolkit.Telemetry ERROR TelemetrySend::_doPing - error making request to https://incoming-telemetry.thunderbird.net/submit/telemetry/71edf4f0-03fe-4953-aa27-e3bb9bda0ead/first-shutdown/Thunderbird/91.4.1/release/20211216022855?v=4: eUnreachable Log.jsm:723 16:57:59.710 1642093079710 Toolkit.Telemetry ERROR TelemetrySend::sendPersistedPings - failed to send ping 71edf4f0-03fe-4953-aa27-e3bb9bda0ead: {"isTrusted":true} Log.jsm:723 16:57:59.712 1642093079712 Toolkit.Telemetry ERROR TelemetrySend::_doPing - error making request to https://incoming-telemetry.thunderbird.net/submit/telemetry/2746998c-06ea-4588-a484-945dbeef945a/main/Thunderbird/91.4.1/release/20211216022855?v=4: eUnreachable Log.jsm:723 16:57:59.712 1642093079712 Toolkit.Telemetry ERROR TelemetrySend::sendPersistedPings - failed to send ping 2746998c-06ea-4588-a484-945dbeef945a: {"isTrusted":true} Log.jsm:723 16:57:59.713 1642093079713 Toolkit.Telemetry ERROR TelemetrySend::_doPing - error making request to https://incoming-telemetry.thunderbird.net/submit/telemetry/7a002b16-f843-46d5-b637-8f7920a52abb/first-shutdown/Thunderbird/91.4.1/release/20211216022855?v=4: eUnreachable Log.jsm:723 16:57:59.713 1642093079713 Toolkit.Telemetry ERROR TelemetrySend::sendPersistedPings - failed to send ping 7a002b16-f843-46d5-b637-8f7920a52abb: {"isTrusted":true} Log.jsm:723

<blockquote> NS_ERROR_NOT_IMPLEMENTED: Component returned failure code: 0x80004001 (NS_ERROR_NOT_IMPLEMENTED) [nsIRequest.name] 4 OAuth2.jsm:171 </blockquote> This could be related, but it's neither exactly clear what's causing the error, nor is there an obvious solution. I'd suggest to create a new profile using profile manager, start TB with the new profile, and set up one of the troubled Gmail accounts in the new profile. https://support.mozilla.org/kb/using-multiple-profiles Is there any difference?

I added a second profile - see screen shot. It gave the same error screen :-(

I wonder if OAuth2 is the trigger here?

I have now deleted the new profile and started again with screenshots... Screen 1: Create profile

Screen 2: Create Profile Wizard - click Next

Screen 3: Enter new profile name

Screen 4: New profile name entered - click Finish

Screen 5: Click on the new profile name and ensure both checkboxes are unchecked.

Screen 6: Exit from the profile manager and start Thunderbird

Screen 7: Fill out the email address/password form and click Continue

Screen 8: Thunderbird fails to fill in the details, so fill them in manually.

Screen 9: Click Re-test - connection security is automatically changed to SSL/TLS. Authentication methods both remain as Autodetect. Click Re-test again.

Screen 10: Re-test sets both Authentication methods to Normal password. Click Done

Screen 11: ERROR: Unable to log in at Server ...

Screen 12: This is the "Problem loading page" tab