A. 1. Switch to Wi-Fi: If possible, connect to a Wi-Fi network to see if ticket validation works better. 2. Check mobile data settings: Ensure that the app has permission to use mobile data. Go to Settings > Apps > BudapestGO > Data usage and enable mobile data if it's disabled.

B. 3. Restart the app: Close the app completely and reopen it to refresh the session. 4. Update the app: Ensure you have the latest version of BudapestGO from the Google Play Store.