Indicator Applet Crashes with unity::indicator::datetime::DateTime::get() const: assertion failed: (m_dt)

I added some debugging output to the DateTime class to create stacktrace when a DateTime is assigned whose `m_dt` field is a `nullptr`.

The following is the stack trace when this happens:
./indicator-datetime-service(_ZN5unity9indicator8datetime8DateTimeaSERKS2_+0x45)[0x55abe5d8ba6f]
./indicator-datetime-service(_ZN5unity9indicator8datetime9EdsEngine4Impl15get_appointmentEP11_ECalClientRSt10shared_ptrI13_GCancellableEP14_ECalComponentP10_GTimeZone+0x1c4)[0x55abe5d9210f]
./indicator-datetime-service(_ZN5unity9indicator8datetime9EdsEngine4Impl20add_event_to_subtaskEP14_ECalComponentPNS3_13ClientSubtaskEP10_GTimeZone+0x9c)[0x55abe5d92ce3]
./indicator-datetime-service(_ZN5unity9indicator8datetime9EdsEngine4Impl24on_event_fetch_list_doneEPv+0x21c)[0x55abe5d9171f]
./indicator-datetime-service(_ZN5unity9indicator8datetime9EdsEngine4Impl24fetch_detached_instancesEP8_GObjectP13_GAsyncResultPv+0xe5)[0x55abe5d91221]
./indicator-datetime-service(_ZN5unity9indicator8datetime9EdsEngine4Impl29on_event_generated_list_readyEPv+0x26)[0x55abe5d9131f]
/lib/x86_64-linux-gnu/libecal-2.0.so.1(+0x25d85)[0x7f2834aedd85]
/lib/x86_64-linux-gnu/libecal-2.0.so.1(+0x2d204)[0x7f2834af5204]
/lib/x86_64-linux-gnu/libgio-2.0.so.0(g_simple_async_result_complete+0x86)[0x7f28346405c6]
/lib/x86_64-linux-gnu/libgio-2.0.so.0(+0xa068f)[0x7f283464068f]
/lib/x86_64-linux-gnu/libglib-2.0.so.0(g_main_context_dispatch+0x14e)[0x7f2834468e8e]
/lib/x86_64-linux-gnu/libglib-2.0.so.0(+0x52240)[0x7f2834469240]
/lib/x86_64-linux-gnu/libglib-2.0.so.0(g_main_loop_run+0x83)[0x7f2834469533]
./indicator-datetime-service(main+0x59b)[0x55abe5d5dffb]
/lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xf3)[0x7f28340450b3]
./indicator-datetime-service(_start+0x2e)[0x55abe5d5ccee]

Ah, I see the comment box breaks lines. I add it as an attachment here.

After investigating a bit more, the issue is probably that `e_cal_component_get_dtstart` returns a nullptr for a call in get_appointment in EdsEngine.

Status changed to 'Confirmed' because the bug affects multiple users.

SUMMARY

For me, the fix was to delete a recently-created task in Evolution.

DETAILS

I encountered this error a few hours ago, after I added a task in Evolution (something I rarely do). I set three reminders for the task. Within 10 minutes, the datetime indicator applet froze at 16:40. The Date tab in the Date/Time settng applet was also greyed-out, so I was unable to turn it back on. I re-booted three times, hoping it was an update issue, but all I saw was the datetime indicator crash repeatedly and then vanish within seconds of my logging in.

I searched /var/log/syslog for "crash" and found it was the datetime-indicator service that had crashed. I was able to confirm this with the following command:

systemctl status indicator-datetime --user

I tried restarting it, but I got a message that the service had crashed too many times.

Since I was fairly certain that this was related to the Evolution Task that I just created, I deleted it, restarted the service, and the datetime indicator came back.

Hopefully, this will help someone else.

Thanks iPadGuy,

I can confirm that task creation via Evolution triggers the issue.
After following your instructions and relaunching the indicator-datetime service, the indicator correctly reappeared in the indicator tray.