The following error message appears during business cards' synchronization:

Synchronization failed. Try again? The operation couldn't be completed (error 400).

To prevent the loss of business cards, please create a backup copy of your Cardholder:

1. Start BCR;
2. Tap Settings;
3. Select Cardholder > Backup;
4. Follow the instructions on the screen.

Next, please log out and log in to the app:

1. Launch BCR;
2. Go to Settings;
3. Tap ABBYY Account > Sign Out;
4. Tap Log in and enter your email and password.