Older versions of the COROS iPhone app cannot connect to COROS servers after September 16, 2026. How to fix: Update the COROS app from the App Store to version V4.9.11 or later. This only affects the iPhone app; the Android app is not affected.
What's happening
The COROS app uses a security certificate to make a secure connection to our servers. The certificate used by older versions of the iPhone app expires on September 16, 2026. After that date, those versions can't connect.
Your account, activity history and settings are not affected.
Who's affected
You may be affected if you see any of the following issues after September 16, 2026:
- A "network error" or "connection failed" message in the COROS app
- Your watch not syncing with the app
- Your latest data not loading in the app
This only affects iPhone users on a COROS app version older than V4.9.11. The Android app is not affected.
How to fix it
- Open the App Store on your iPhone.
- Search for COROS.
- Tap Update. If you see Open instead, you already have the latest version.
- Open the COROS app and sync your watch.
You need version V4.9.11 or later. If the app still won't connect even after updating, try these steps:
- Close the COROS app completely and reopen it.
- Turn Bluetooth off and back on in Settings > Bluetooth.
- Sign out of the COROS app and sign back in.
- Check that your iPhone is connected to Wi-Fi or mobile data.
How to check your app version
On your iPhone, go to Settings > General > iPhone Storage and tap COROS. The version number is under the app name.
Get future updates automatically
Go to Settings > App Store and turn on App Updates.
Need more help?
If it still won't connect, contact COROS Support and include the following details:
- Your iPhone model and iOS version (found in Settings > General > About)
- Your COROS app version (found in Settings > General > iPhone Storage > COROS)
- Screenshots of the error message(s)
FAQs
Will I lose any data?
No. Everything you've synced is stored in your COROS account. If you recorded any activities on your watch that are not syncing to the app, do not uninstall the app or reset your watch. Instead, please take photos of the unsynced workouts from your watch's history widget, and contact our support team so we can assist.
Was my account compromised?
No. Security certificates have a set expiration date and are replaced on a schedule. Your account and data are unaffected.
I opened the app recently. Do I still need to update?
We sent a configuration change to the app on September 12–13 that moves many older versions over automatically. Updating to V4.9.11 is still the surest way to keep connecting.