Calendar Sync Not Working? Find Where the Update Stops

Follow one missing update from its source to its destination. Find the last place where the appointment is correct and the first place where it is wrong. This works for account sync, subscriptions, desktop add-ins, automations, and copying services, and lets you fix the failed step without reconnecting every account.

Write down the route

Use plain account names, for example:

Personal Google calendar → copying rule → Microsoft work calendar → Outlook on phone

That is different from:

University feed → Google subscription → Google Calendar app

Identify whether the route uses a subscription, a shared original, or event copies, since each handles changes differently.

Choose a test appointment without guests. Record the expected date, time, and destination. Avoid using a confidential or business-critical meeting for experiments.

The original provider's website

Open the original account in a browser. Is the appointment there, and is its latest change correct?

If it only exists on a phone, inspect the event's selected calendar. It may be in a local calendar or another account. Google specifically recommends checking the account associated with newly created events in its app sync guide.

If iCloud is the source, Apple recommends checking service status, the signed-in account, and calendar settings before deeper changes. Follow its iCloud troubleshooting guide.

Until the original reaches its server, another service cannot reliably read the update.

The connection or copying step

Once the source is correct, inspect the next connection.

For a native account connection, check whether sign-in is still valid and the calendar is enabled. For a desktop add-in, confirm the computer and required application are running. For an automation, inspect the last run and whether it handles updates, not just new events.

For an ICS subscription, confirm it uses a live URL. An imported file will not receive updates. Investigate the publisher's feed and subscriber refresh if a published change has not arrived.

For an Avum copy, open its Sync Rule and confirm the source calendar, writable destination, direction, active state, and filters. An event intentionally excluded by a rule is different from a connection failure. Do not create another identical rule to compensate for a broken one.

The receiving calendar's website

Open Google Calendar, Outlook on the web, iCloud.com, or the relevant CalDAV provider independently of the phone app.

If the destination website has the correct event, cross-account copying may have succeeded. The remaining problem is the destination app's own refresh, calendar selection, or account connection.

If the destination website is wrong too, the problem lies earlier. Check account access, whether the source event matches the rule, and whether the destination allows writes. A shared read-only calendar can appear in a list without being a suitable destination.

Availability, time zones, and recurring exceptions

An appointment can arrive correctly yet fail to block availability. Inspect its Busy/Free setting and the calendars selected by the booking service. Ask a colleague to check the relevant free/busy view.

For a one-hour difference, compare time zones before moving the event; daylight-saving transitions can change local meeting times. If only one recurring exception is wrong, inspect that occurrence and its source.

Use the calendar sync checks to isolate the event types that fail.

Information to send to support

Record the source and destination providers, calendar names, app versions, test time, expected result, and exact error. Explain where the event last looked correct. Redact personal details and never include passwords or full private feed URLs.

Change the smallest relevant setting and run the same test again. Then you can tell whether that change fixed the problem.

Ready to try a controlled copying setup after tracing the issue? Start your free 30-day trial with Avum today.