When creating events in Google Calendar, many developers come across the error message: Calendar usage limits exceeded. This happens even when they are not exceeding the API quota.

Error - usage limits exceeded

The full error response is the following:

{
      domain: 'usageLimits',
      reason: 'quotaExceeded',
      message: 'Calendar usage limits exceeded.'
}

The corresponding Calendar API request might look like the following:

POST https://www.googleapis.com/calendar/v3/calendars/primary/events
Authorization: Bearer [YOUR_ACCESS_TOKEN]
Accept: application/json
Content-Type: application/json
{
  "attendees": [
    {
      "email": "[email protected]"
    },
    {
      "email": "[email protected]"
    }
  ],
  "end": {
    "date": "2024-01-02"
  },
  "start": {
    "date": "2024-01-01"
  },
  "summary": "A Calendar Event"
}

Cause - spam prevention

The reason for this is to prevent spam and is triggered by the following:

• Sending notifications to attendees
• Including attendees that are external to the Google Workspace domain, e.g. inviting [email protected] from [email protected].

Solution - remove attendees

The problem is only fixed by removing the attendees and using an alternative approach. In the case of external domains, and sending notifications, the following are some alternatives:

• Provide a template link for users to create an event in their Google Calendar.
• Use .ics files to create events in any calendar application.
• Use OAuth to modify the user’s calendar directly.
• Share a public Google Calendar and add events to it.
• Use the publish event feature in Google Calendar to embed HTML.

Google Calendar template links look like the following:

https://calendar.google.com/calendar/r/eventedit
  ?action=TEMPLATE
  &dates=20230325T224500Z%2F20230326T001500Z
  &stz=Europe/Brussels
  &etz=Europe/Brussels
  &details=EVENT_DESCRIPTION_HERE
  &location=EVENT_LOCATION_HERE
  &text=EVENT_TITLE_HERE

Resources

• Avoid Calendar use limits
• Google Calendar API public issue tracker
• Calendar sharing through the API
• Inviting attendees to an event
• Google Calendar template link