>>> [!note] Migrated issue <!-- Drupal.org comment --> <!-- Migrated from issue #3252918. --> Reported by: [texas_tater](https://www.drupal.org/user/753614) Related to !2 >>> <h3 id="summary-problem-motivation">Problem/Motivation</h3> <p><em>NOTE: Both of the following problems have been confirmed to originate from the same root cause:</em></p> <ul> <li>.ics files generated from events cannot be imported into the latest version of Outlook for Mac</li> <li>.ics files generated from events and imported into Outlook for Windows are imported with a start and end time one hour later than the actual event</li> </ul> <p>The iCalendar spec describes the required <code>VTIMEZONE</code> calendar component.</p> <p>From <a href="https://icalendar.org/iCalendar-RFC-5545/3-6-5-time-zone-component.html">https://icalendar.org/iCalendar-RFC-5545/3-6-5-time-zone-component.html</a>:</p> <blockquote><p>The "VTIMEZONE" calendar component MUST include the "TZID" property and at least one definition of a "STANDARD" or "DAYLIGHT" sub-component. The "STANDARD" or "DAYLIGHT" sub-component MUST include the "DTSTART", "TZOFFSETFROM", and "TZOFFSETTO" properties.</p> <p>An individual "VTIMEZONE" calendar component MUST be specified for each unique "TZID" parameter value specified in the iCalendar object. In addition, a "VTIMEZONE" calendar component, referred to by a recurring calendar component, MUST provide valid time zone information for all recurrence instances.</p></blockquote> <p>Per that spec, the <code>VTIMEZONE</code> calendar component currently being generated for .ics downloads by the addtocal_augment contrib module is missing the required <code>DTSTART</code> attribute on the <code>STANDARD</code> sub-component, as shown in this example:</p> <pre>BEGIN:VTIMEZONE<br>TZID:America/Chicago<br>BEGIN:STANDARD<br>TZOFFSETFROM:-0500<br>TZOFFSETTO:-0500<br>END:STANDARD<br>END:VTIMEZONE</pre><p>Different calendar clients respond differently when attempting to import an ics file with this malformed <code>VTIMEZONE</code> component.</p> <ul> <li>Some import with no problem (Google Calendar, Outlook Web Access)</li> <li>Some import with a one hour offset on the time, due to missing daylight savings time definition (Outlook for Windows)</li> <li>Some fail to import, with an undefined error (Outlook for Mac)</li> </ul> <h4 id="summary-steps-reproduce">Steps to reproduce</h4> <h5>Problem 1 - Failure to import into Outlook for Mac</h5> <ol> <li>Using a Mac, click "Add to Calendar" on a event in a UTDK site and select the "Outlook" format</li> <li>Drag the download event.ics file onto the Outlook icon in the Dock</li> <li>Confirm "Import" in the "Add Event" dialog</li> <li>Should receive an error message that says "Sorry we couldn&rsquo;t import some of your file(s). Please try again later."</li> </ol> <h5>Problem 2 - Incorrect time display after import into Outlook for Windows</h5> <ol> <li>Using a Windows computer, click "Add to Calendar" on a event in a UTDK site and select the "Outlook" format</li> <li>Confirm the import into Outlook for Windows</li> <li>The event should display in Outlook with a start and end time one hour later than the time displayed on the website</li> </ol> <h3 id="summary-proposed-resolution">Proposed resolution</h3> <p>Remove the <code>VTIMEZONE</code> component from the generated ics file altogether, and express the <code>DTSTART</code> and <code>DTEND</code> components in UTC.</p> <p>Example:</p> <pre>BEGIN:VCALENDAR<br>PRODID:Example site name<br>VERSION:2.0<br>BEGIN:VEVENT<br>UID:2adaf962-ab23-4e97-b38d-9984edd1036b<br>SUMMARY:Example event title<br>DTSTAMP:20230503T081300Z<br>DTSTART:20230510T180000Z<br>DTEND:20230510T190000Z<br>DESCRIPTION:Example event description<br>LOCATION:Example event location<br>END:VEVENT<br>END:VCALENDAR</pre><p>This removes the responsibility for constructing a valid <code>VTIMEZONE</code> component from the module, produces a valid ics file, and allows the calendar client importing the ics file to display the event in the selected time zone of the user.</p> <p>This approach is similar to that used by all of the major calendar programs -- Google Calendar, Microsoft Outlook, and Apple Calendar -- in their ics exports. Regardless of the user's timezone, events from those calendar systems are exported with the start and end time expressed in UTC.</p> <h3 id="summary-remaining-tasks">Remaining tasks</h3> <h3 id="summary-ui-changes">User interface changes</h3> <h3 id="summary-api-changes">API changes</h3> <h3 id="summary-data-model-changes">Data model changes</h3>