If you find a problem, try to <a href="https://support.mozilla.org/kb/troubleshoot-mode-thunderbird">reproduce the problem in Troubleshoot Mode</a>, then file a bug report for <a href="https://bugzilla.mozilla.org/enter_bug.cgi?product=Thunderbird">Thunderbird</a> or <a href="https://bugzilla.mozilla.org/enter_bug.cgi?product=Calendar">Calendar</a>.
If you find a problem, try to <a href="https://support.mozilla.org/kb/troubleshoot-mode-thunderbird">reproduce the problem in Troubleshoot Mode</a>, then file a bug report for <a href="https://bugzilla.mozilla.org/enter_bug.cgi?product=Thunderbird">Thunderbird</a> or <a href="https://bugzilla.mozilla.org/enter_bug.cgi?product=Calendar">Calendar</a>.