Calendar not syncing, or events not showing up on a second device? This page helps you find the cause and fix it step by step.

1

How sync works

aCalendar does not synchronize your calendars itself. It only displays what Android stores locally. The actual sync is always handled by your cloud service (e.g. Google, Exchange, CalDAV) – not by aCalendar.

The “Synchronization” button in aCalendar simply tells Android to ask all cloud services to sync. If sync still doesn’t happen automatically, battery saving settings are the most common cause.

All standard Android calendar apps – such as the Samsung Calendar app – display the same calendar data from Android’s shared calendar storage. If your data shows up correctly in another calendar app, it will show up in aCalendar too.

The exception is apps like Microsoft Outlook, which use their own private sync and do not share data with the Android calendar system.

2

Service- or device-specific help

For some services and devices there are dedicated help pages with more detail:

Google Calendar sync issues

Problems specific to Google Calendar synchronization.

Microsoft Exchange, Hotmail, Outlook.com, Office 365

Setup and known issues for all Microsoft cloud services and corporate Exchange accounts.

CalDAV (ownCloud, Synology, Yahoo, etc.)

Setting up CalDAV-based calendar services via DAVx⁵.

OnePlus devices

Known sync issues specific to OnePlus phones.

Xiaomi devices

Known sync issues specific to Xiaomi phones.

Sync error codes and messages

What the sync error messages in aCalendar mean and what to do about them.

3

General troubleshooting steps

Work through these steps in order. If sync works on one device but not another, start by testing each device individually against the web interface of your cloud service (e.g. calendar.google.com).

1

Check Android account & sync settings

Go to Settings → Accounts on your phone and make sure sync is enabled for your calendar account. You can also reach this directly from aCalendar: Menu → Manage Calendars → three dots (top right) → Android Account/Sync Settings.

2

Check global sync settings

Make sure Auto-sync is enabled globally on your device. On some phones this is found under Settings → Accounts → Auto-sync data.

3

Check background data settings

Make sure background data is not restricted for the Gmail app or your calendar sync app. Go to Settings → Apps → Gmail → Mobile data and check that “Background data” is enabled.

4

Check battery saving options

Battery saving modes can block apps from syncing in the background. Check your power saving settings and make sure the Gmail app and your calendar sync service are excluded from any restrictions.

If none of the above helps, check the help and support pages of your specific cloud service – the issue is almost always on the sync side, not in aCalendar.

4

New calendars & backups

You can create new calendars directly from the Calendar List (Menu → Manage Calendars). There are two types:

Local calendar

Stored only on your phone – no cloud sync. This means no automatic backup. If your phone breaks or gets lost, the data is gone. Make sure to back up local calendars manually and regularly.

Google Calendar

Synced to your Google account – automatically backed up in the cloud. This is the most reliable option and best integrated with aCalendar.

Other cloud services (Exchange, CalDAV, etc.): new calendars must be created directly in the cloud service itself – not in aCalendar. Once created, they will appear in aCalendar automatically after the next sync.