Android Contacts not Syncing with Exchange / Office 365

If you use the Microsoft Outlook app to sync contacts, you can reset the account within the app itself. This clears the app's local cache without deleting the account.

1. Open the Outlook app.
2. Tap your profile icon (top left) and then the Settings (gear) icon.
3. Tap on the specific Exchange/365 account that is failing.
4. Scroll down and tap Reset Account. The app will restart and re-sync your data.
5. Ensure Sync Contacts is still toggled ON in these same settings.

If Method 1 fails, or if you sync via the native Android "ActiveSync" settings, you need to clear the system-level contact storage.

Warning: This will remove all locally stored contacts and call logs. It will not delete contacts stored in the cloud (Office 365, Google, etc.), but it will force a full re-download. Back up any "Phone-only" contacts before proceeding.

1. Go to your phone Settings > Apps (or Manage Apps).
2. Tap the three dots (top right) and select Show system apps.
3. Find and tap on Contacts Storage.
4. Tap Storage > Clear Data (and Clear Cache).
5. Now, find the Contacts app in that same list and Clear Cache for that as well.
6. Restart your phone.
7. Wait 5–10 minutes for the background sync to pull the data from the 365 servers.