Lightning doesn't load data, won't open calendar tab

[Duokar]

TB 52.8.0, Lightning 5.4 Win10. The only other add-on I have installed besides Lightning is "Clean Subject 0.4.3". I've tried disabling it but that doesn't help.

When I open Thunderbird, Lightning does not load any data. The today pane is empty and I can't open a calendar tab. Obviously, that's a problem. It has happened rarely in recent history but now happens every time.

I've copy/pasted the error console messages below. The Mutation Event warning and calTimezoneService.js error "Couldn't find Eastern Time" hopefully means something to someone. If I change the time zone setting for TB/L and for the PC itself to some other time zone, the error still says Eastern time. The error console text is copy/pasted in full:

** Preference parsing warning (line 1) = preserving unexpected JS escape sequence **

[calTimezoneService] Loading resource://calendar/timezones/zones.json calTimezoneService.js:76:13
[calTimezoneService] Timezones version 2.2016j loaded calTimezoneService.js:127:13
Use of Mutation Events is deprecated. Use MutationObserver instead. calendar-widgets.xml:506:18
Couldn't find Eastern Time calTimezoneService.js:199:13
NS_ERROR_NOT_AVAILABLE: Cannot call openModalWindow on a hidden window nsPrompter.js:351
Error: Script terminated by timeout at:
setBusyDaysForOccurrence@chrome://calendar/content/widgets/minimonth.xml:576:1
onGetResult@chrome://calendar/content/widgets/minimonth.xml:501:15
calCompositeGetListenerHelper.prototype.onGetResult@file:///C:/Users/agenm/AppData/Roaming/Thunderbird/Profiles/1briwfwc.default/extensions/%7Be2fda1a4-762b-4020-b5ad-a41df1933103%7D/components/calCompositeCalendar.js:532:9
queueItems@file:///C:/Users/agenm/AppData/Roaming/Thunderbird/Profiles/1briwfwc.default/extensions/%7Be2fda1a4-762b-4020-b5ad-a41df1933103%7D/components/calStorageCalendar.js:753:17
handleResultItem@file:///C:/Users/agenm/AppData/Roaming/Thunderbird/Profiles/1briwfwc.default/extensions/%7Be2fda1a4-762b-4020-b5ad-a41df1933103%7D/components/calStorageCalendar.js:784:13
calStorageCalendar.prototype.getItems_@file:///C:/Users/agenm/AppData/Roaming/Thunderbird/Profiles/1briwfwc.default/extensions/%7Be2fda1a4-762b-4020-b5ad-a41df1933103%7D/components/calStorageCalendar.js:858:30
calStorageCalendar.prototype.getItems/<@file:///C:/Users/agenm/AppData/Roaming/Thunderbird/Profiles/1briwfwc.default/extensions/%7Be2fda1a4-762b-4020-b5ad-a41df1933103%7D/components/calStorageCalendar.js:664:13
minimonth.xml:576:1
NS_ERROR_FAILURE: Component returned failure code: 0x80004005 (NS_ERROR_FAILURE) [calIOperationListener.onGetResult] calStorageCalendar.js:753
PAC file installed from http://proxypac.mitre.org/sys/proxy.pac
live.mozillamessaging.com:443 uses an invalid security certificate.

The certificate is not trusted because the issuer certificate is unknown.
The server might not be sending the appropriate intermediate certificates.
An additional root certificate may need to be imported.

Error code: <a id="errorCode" title="SEC_ERROR_UNKNOWN_ISSUER">SEC_ERROR_UNKNOWN_ISSUER</a>
(unknown)
DEPRECATION WARNING: The arguments you're passing to viewSource.xul are using an out-of-date API.
You may find more details about this deprecation at: https://developer.mozilla.org/en-US/Add ... plications
chrome://global/content/viewSource.js 329 _loadViewSourceDeprecated
chrome://global/content/viewSource.js 309 onXULLoaded
chrome://global/content/viewSource.js 175 handleEvent
Deprecated.jsm:79
addons.cdn.mozilla.net:443 uses an invalid security certificate.

The certificate is not trusted because the issuer certificate is unknown.
The server might not be sending the appropriate intermediate certificates.
An additional root certificate may need to be imported.

Error code: <a id="errorCode" title="SEC_ERROR_UNKNOWN_ISSUER">SEC_ERROR_UNKNOWN_ISSUER</a>
(unknown)
http://www.thunderbird.net:443 uses an invalid security certificate.

The certificate is not trusted because the issuer certificate is unknown.
The server might not be sending the appropriate intermediate certificates.
An additional root certificate may need to be imported.

Error code: <a id="errorCode" title="SEC_ERROR_UNKNOWN_ISSUER">SEC_ERROR_UNKNOWN_ISSUER</a>
(unknown)
Security Error: Content at about:neterror?e=nssBadCert&u=https%3A//www.thunderbird.net/calendar/&c=UTF-8&f ... 3C/a%3E%0A may not load or link to chrome://global/skin/icons/warning-16.png.
TypeError: sourceDoc.getSelection is not a function[Learn More] mailWindow.js:74:19

[Daifne]

Moving to the Calendar Forum

[tanstaafl]

Version 52.9.0 installed, Calendar gone. Did I lose all calendar entries???? describes the way to activate the bundled version of Lightning no matter what happened before.

[Duokar]

Unfortunately, that did not work. I followed all the steps. The end result is that Lightning was reinstalled and 'sort of' starts the same way it did before. I can get the today pane but it has no data in it. And the calendar tab won't open. The error console still gives the same errors about

Use of Mutation Events is deprecated. Use MutationObserver instead. calendar-widgets.xml:506:18
Couldn't find Eastern Time calTimezoneService.js:199:13

I am on 52.9.0 now.