Why Your External Calendars Aren’t Showing on the Calendar

If a Google, Apple, or other external calendar isn’t appearing inside Helium, the issue is usually related to the External Calendar settings, an invalid URL, or the feed being automatically disabled after an error. This guide walks you through the most common causes and how to fix them.

1. Check Calendar Filters

• If "Remember filter selections" is enabled, Helium may be hiding items from a previous session
  • This can be disabled in Account → Settings → Preferences
• When filters are applied, the dropdowns are blue instead of grey
• Make sure filters aren't applied, or if they are, that "External Calendars" is one of the selected filters

2. Wrong View

• The "Todos" view only shows "Assignments", so "External Calendars" will not appear here

2. The External Calendar Is Not Enabled

Each external calendar in Helium has an Enabled checkbox. If this not checked, it will not be shown on the Calendar.

Important: If Helium encounters an error while loading an External Calendar (for example, an invalid or unreachable URL), it will automatically disable the calendar. If your calendar disappears, this is the most likely cause.

How to Check

1. Go to Account → Settings → Preferences
2. Scroll to the External Calendars section
3. Find your calendar in the list
4. Make sure the Enabled checkbox is selected

If the checkbox keeps unchecking itself, the URL may be invalid — see the steps below.

3. The iCal/ICS URL Is Incorrect or Invalid

The URL for an External Calendars must return a valid iCal/ICS calendar. HTML links to a webpage or Google Calendar’s "share" URL will not work.

Check the following:

• The link ends with .ics (not required, but a common practice)
• The link was copied from your calendar app's "Subscribe" or "Add by URL" option (see How to Sync Google, Apple, or Other Calendars in Helium (External Feeds))
• There are no extra spaces before or after the URL

If the URL is invalid, Helium will disable the feed automatically the next time it tries to load it.

4. Your Calendar App’s iCal/ICS URL Changed

Some services rotate or invalidate feed URLs after account changes (e.g., changing your password, switching accounts, or adjusting privacy settings). If the feed suddenly stopped working:

• Re-copy the URL from Google or Apple Calendar (see How to Sync Google, Apple, or Other Calendars in Helium (External Feeds))
• Update it in Helium

5. The External Calendar Is Refreshing Slowly

Helium refreshes External Calendars on a period basis. If the source calendar updates slowly, the calendar provider caches the feed, or Helium is busy, changes may take time to appear. This is normal.