If you were stood-up for lunch or no one showed for an important business meeting, there may be a good reason: Google Calendar crashed. The online and in-app calendar keeps the schedules of millions of people and companies every minute of the day.

For three hours Tuesday morning, Google cleared the calendars of millions of users around the world. When trying to see appointments and events on Google Calendar, we saw this: an error code and a page that would never open.

First reported before most people reported for work Tuesday, soon it appeared that, without Google Calendar, no one knew what they were supposed to do.

Google's calendar app worked okay. You could see your schedule but could not add anything. It also wasn't working with Gmail and other G-suite applications.

Down detector showed Google Calendar users around the world reported the outage.

Nearly three hours later, Google issued a statement saying its back up, but did not say what happened.

The outage comes just after some Google users noticed malware being added to their calendar. Security firm "Kaspersky" discovered bad actors were sending spam and malware through Google Calendar invites.

Whether or not these two events are connected is unclear. But if you use Google Calendar to schedule all of your meetings, appointments and events, it's a good idea to back up that work on another calendar app such as the one from Apple, or Microsoft or a calendar app such as "Fantastical 2.”

The Google Calendar outage follows other Google problems. Earlier this month many users could not access their Gmail accounts or access YouTube.