The Mozilla Calendar project also known as Lightning (more info).

Select a component to see open bugs in that component:


For issues with alarms for scheduled events and tasks.

Build Config

Archive for Calendar-specific build configuration bugs. Please use Thunderbird :: Build Config for future issues.

Calendar Frontend

For issues concerning frontend components in calendar that are not dialogs, e.g. the calendar views, calendar list, events list (unifinder).


For issues with the calendar, event, and task dialogs.

E-mail based Scheduling (iTIP/iMIP)

For issues with E-mail based scheduling, e.g. accepting invitations or sending out invitations, replies etc.


For issues which don't fit in a more specific Calendar component.

ICAL.js Integration

Bugs within the integration layer for the ICAL.js library from . For issues with the library itself (i.e in calendar/base/modules/ical.js), please file an issue on github. This component is about the wrapper interface between xpcom and ICAL.js

Import and Export

For issues with format conversions (for importing, exporting, emailing, cutting, pasting, dragging, and dropping to/from another application).

Internal Components

For issues with the internal interfaces of the calendar components. Bug example: Incorrect timezone calculations.

Lightning Only

Archive for issues that only affect the Lightning product. This is from the time where calendar was an extension.

Lightning: SeaMonkey Integration

Archive for issues that only affect the Lightning product on SeaMonkey. Please see SeaMonkey :: Calendar instead

OS Integration

Archive for areas where Calendar integrates with the host desktop environment. Please use Calendar :: Internal Components instead.


Issues related to calendar preferences.


For issues with printing.

Provider: CalDAV

For issues with CalDAV server communication

Provider: GData

Archive for issues regarding the 'Provider for Google Calendar' extension. Please see for future issues.

Provider: ICS/WebDAV

For issues regarding communicating with .ics files via remote (http:) and local (file:) URIs.

Provider: Local Storage

For issues regarding local calendar storage, based on mozStorage (SQLite).

Provider: WCAP

Archive for issues with the WCAP provider.


Archive For app-level security bugs. Please file in the respective components and mark them as security issues instead.

Sunbird Only

Archive for issues that only affect the Sunbird product. This was a standalone calendaring application based on Gecko with a shared code base.


For issues with Task lists, display, editing, and searching.


Archive for Calendar Project Website issues. Since Calendar is integrated into Thunderbird please use for website issues.