Summary

Events in Team Calendar are no longer appearing when exporting the calendar to Outlook. The problem happens on both Outlook webmail and Outlook desktop client (Windows and Mac). This article will help you treat the problem but also clarify how Outlook synchronization works.

The following article – import or subscribe to a calendar in Outlook on the web – describes how long it can take for the events from an external calendar can take to sync with Outlook:

"Subscribing to an iCal online calendar connects it to your calendar. Whenever the owner of an iCal you've subscribed to makes changes to the events, Outlook on the web updates your calendar. This is a good way to track events that change frequently, like movie times or a school calendar. Note: This update can take more than 24 hours."

If you are running with the fixed version of Team Calendars or Confluence, the error in the log file isn't present, then it's likely the Outlook update time. 

Environment

This problem was identified in Confluence server and datacenter version 7.4.7. It could also affect other versions of Confluence.

Team Calendars version earlier than 7.0.16.

Diagnosis

Steps to reproduce and diagnose the problem:

1. Log into the Outlook webmail
2. Add calendar using Microsoft Outlook (browser) URL from "Subscribe to Team Calendar" calendar app option
3. Team calendar events in Outlook may show or not in Outlook. This may include events before and after the subscription.

The following error appears in the atlassian-confluence.log:

2021-03-25 08:33:50,084 ERROR [http-nio-8090-exec-35] [calendar3.rest.ExceptionMappers.GeneralExceptionMapper] getResponseError General exception happen on calendar resources
-- url: /rest/calendar-services/1.0/calendar/export/subcalendar/private/739df8532dd1c492188d2763bd127957bf3b3fad.ics | traceId: 6f1a2c28a5a15778 | userName: anonymous
javax.ws.rs.WebApplicationException: java.lang.NullPointerException
at com.atlassian.confluence.extra.calendar3.rest.resources.ExportResource.lambda$exportCalendarAsIcalendarTextInternal$0(ExportResource.java:133)
at com.sun.jersey.core.impl.provider.entity.StreamingOutputProvider.writeTo(StreamingOutputProvider.java:71)
...
Caused by: java.lang.NullPointerException
at net.fortuna.ical4j.model.PropertyList.getProperty(PropertyList.java:95)
at net.fortuna.ical4j.transform.command.UidUpdate.transform(UidUpdate.java:19)
at net.fortuna.ical4j.transform.AbstractMethodTransformer.transform(AbstractMethodTransformer.java:37)
at com.atlassian.confluence.extra.calendar3.util.CalendarExportTransformer.transform(CalendarExportTransformer.java:85)
at com.atlassian.confluence.extra.calendar3.DefaultICalendarExporter.getTransformedSubCalendarContent(DefaultICalendarExporter.java:285)
at com.atlassian.confluence.extra.calendar3.DefaultICalendarExporter.export(DefaultICalendarExporter.java:105)

Cause

The application is facing an unexpected NullPointerException. This error is caused by a fixed bug – Subscribing to team calendars via ics/iCal sometimes results in Null Pointer Exception

Solution

Update Team Calendar app to version 7.0.16 or later

If using Confluence Data Center, upgrading Confluence to version 7.12.0 contains the fix. The Team Calendars app is bundled with it.