1849540 - Thunderbird freezes when adding CalDAV calendar with VTIMEZONE

Status: RESOLVED DUPLICATE of bug 1850732

(Calendar :: Provider: CalDAV, defect)

Description

[nils]

Steps to reproduce:

I added a new CalDAV calendar to Thunderbird. To be sure, I've disabled all addons.

Actual results:

After a few seconds, Thunderbird freezes and seems to never come back.

Comment 1

[Copperhead]

Using Thunderbird versions up to 102.14.0 I have subscribed successfully to five calendars using CalDAV.

Starting with Thunderbird 115 I can only subscribe to three of them. As soon as I subscribe to one of the remaining two, Thunderbird freezes using 100% of one of the CPU cores with no progress.

Using the webmail interface, I have exported all fives calendars as iCalender files. I can import three ics-files (which I can subscribe to using CalDAV), the attempt to import one of the remaining two ics-files lets Thunderbird freeze again (progress bar at 0%).

The main difference between the files that I can import and the files that I can't import is the presence of the object VTIMEZONE.

When I remove all the lines from BEGIN:VTIMEZONE to END: VTIMEZONE, I can import the remaining two ics-files, too.

The events in the object VTIMEZONE start back in the days of World War I, when daylight saving was first introduced in the Central European Time zone.

After removing only the first four events of the object VTIMEZONE, it was also possible to import the two problematic ics-files.

I have seen the problem of Thunderbird freezing when subscribing to specific CalDAV calendars or importing the corresponding iCalendar files not only with Thunderbird 115 (up to 115.1.1) but also with Thunderbird Beta version 117 and the Thunderbird Daily 118 (as of Aug 5, 2023).

Comment 2

[Robert Hartmann]

TB 115.2.0. freezes on my end, too.

Can I start a debugging run or profiling run via Windows Command-line option?
As soon the TB Main window is shown, TB blocks and is not responsing to Windows.
Any click with the mouse creates a crash.
(I figured out, if I disconnect from LAN or WLAN, TB did not crash.)

Comment 3

[Dennis Roczek]

(In reply to Robert Hartmann from comment #2)

(I figured out, if I disconnect from LAN or WLAN, TB did not crash.)

I guess because the appointment is not send to the server and thus cannot imported. the problem is on the import base.
I'm having the problem only in creating new calendar entries (through I did not try to create a new calendar nor import any ics except caldav)

Comment 4

[bwilde]

I can also confirm this behavior. I upgraded from Thunderbird 102 to 115 with the calendar subscriptions intact. The first time I tried to create a new appointment in one of the calendars, Thunderbird froze and never recovered. Restarting Thunderbird and trying again lead to the same behavior. Interestingly, the appointments showed up in the calendar's web interface, so Thunderbird was able to place them there. It seems to have frozen only when it tried to synchronize the new appointment on the server.

After this I removed all my calendar subscriptions and tried adding them anew. Adding a new calendar also freezes Thunderbird, probably during the same synchronization step, as the subscription itself is intact: If I kill Thunderbird and restart it, it is still there and leads to Thunderbird freezing again after a few seconds (if I don't unsubscribe before then).

Comment 5

[Robert Hartmann]

Behavior with TB 115.2.2 reproduzible, freeze after importing a Horde CalDAV calendar
(not freeze importing a calendar via AddOn TbSync + Exchange ActiveSync for TbSync).

Comment 6

[Robert Hartmann]

In a clean TB 115.2.2 profile I subscribed a clean empty CALDAV calendar (created via horde Groupware 5.2.22) .
In this TB profile no mail-related configuration I had done.

The subscription of the empty calendar worked well. :-)

Closing TB main window and restarting TB with that profile worked well. :-)

I created one calendar entry via TB.
Via browser interface I could verfy, that TB has pushed the entry to the server. :-)

And after having a look to the horde calendar via Firefox
switching back to the TB window, I could seen the Window Headline "Kalender - Mozillla Thunderbird (Keine Rückmeldung)" .
TB window is frozzen. :-(
If you click some where inside the TB calendar "tableau" the content part of TB window truns into white,
the window border and headline greyed out.
A last click with the mouse on the closing x in the headline , opens a Windows for "wait until responde" or "force quitting".
I'll post a screenshot.

Comment 7

[Robert Hartmann]

Attachment: Attachment for comment 6 (Calendar turns into white, GUI freezed)

Attachement for Bug 1849540 comment 6

Comment 8

[Copperhead]

I have run several tests using TB 115.0 - TB 115.2.2 without any add-on and with the add-ons TbSync and Provider for CalDAV & CardDAV.

I have a set up of calendars served by four different providers using CalDAV. Two providers run Horde Groupware 5.2.23, one provider runs Open-Xchange, I don't know the name of the software that the German Telekom runs (version 7.5.8).

I have seen TB freezing only if two conditions are met:

1. The iCalendar file of the exported CalDAV calendar comprises the VTIMEZONE object.
   and
2. The calendar is provided by the CalDAV server of Horde Groupware.

Using the add-ons TbSync plus Provider for CalDAV & CardDAV does not change the behaviour of TB freezing. The author of these add-ons has pointed out that - starting with his version of the add-ons for TB 102 - the Provider for CalDAV relies on TB's built-in capability to synchronize with CalDAV servers.

Comment 9

[Magnus Melin [:mkmelin]]

Do you have a sample .ics file you can attach for reproduction?

Comment 11

[Copperhead]

Attachment: My calendar with VTIMEZONE

@Magnus Melin
Using webmail (Horde Groupware) I have created an empty calendar.
Using TB 115.2.2 I have subscribed to this CalDAV calendar and added several all day events to it.
TB did not freeze.
Using webmail I have exported this calendar. I did not contain the VTIMEZONE object.

Then I added another event, providing a start and an end time. TB froze immediatly.

Using webmail I verified that the most recently added event was present and exported the calendar again. This time the iCalendar contained a VTIMEZONE object.

my_calendar.ics:

Comment 12

[Copperhead]

Attachment: my_calendar.ics

@Magnus Melin
Using webmail (Horde Groupware) I have created an empty calendar.
Using TB 115.2.2 I have subscribed to this CalDAV calendar and added several all day events to it.
TB did not freeze.
Using webmail I have exported this calendar. I did not contain the VTIMEZONE object.

Then I added another event, providing a start and an end time. TB froze immediatly.

Using webmail I verified that the most recently added event was present and exported the calendar again. This time the iCalendar contained a VTIMEZONE object.

Comment 13

[Robert Hartmann]

Attachment: Mittagessen.ics (exported via Horde, infos written by TB into Horde, TB could not import ics)

In Bug 1849540 comment 6 I had created a test calendar entry. This ics file was generated by horde export funktion. TB could not reimport (its own information given to horde).

Comment 14

[Copperhead]

@Magnus Melin
Using webmail (Horde Groupware) I have created an empty calendar.
Using TB 115.2.2 I have subscribed to this CalDAV calendar and added several all day events to it.
TB did not freeze.
Using webmail I have exported this calendar. I did not contain the VTIMEZONE object.

Then I added another event, providing a start and an end time. TB froze immediatly.

Using webmail I verified that the most recently added event was present and exported the calendar again. This time the iCalendar contained a VTIMEZONE object.

---

I'm sorry, I tried to upload the .ics file but it failed. This is the corresponding error message:
"Couldn’t upload the text as an attachment. Please try again later. Error: Failed to fetch attachment ID 9352905 from S3: The requested key was not found"

Comment 15

[Robert Hartmann]

Attachment: TB115.2.2_Freezing-ICS-Import.png

Screenshot just shows a frozen TB-Window while import ICS file from Bug 1849540 comment 13.

Comment 16

[Sean Burke [:leftmostcat]]

Merging into a later bug as the later bug has specific details on the RRULE causing problems. In summary, Horde generates invalid recurrence rules in its time zone definitions. Per the iCalendar spec, we should be ignoring these, but we fail to detect them and loop infinitely looking for an occurrence.