A tamper error means your terminal's built-in security has detected a physical threat to the device and has locked itself to protect your payment data. You can't fix this yourself. Keep the terminal powered off and contact Mollie support.
What you need to know in advance
- Tamper protection is a security feature, not a bug. It's designed to permanently disable a terminal the moment it detects it may have been opened, forced, or damaged, so that payment data can never be extracted.
- This article covers the PAX A920 Pro and PAX A35.
- Once a tamper error appears, the terminal's encryption keys are cleared automatically. This can't be undone and isn't something support can reverse remotely.
Regardless of the device or the app you use, always report tamper events - or suspicions of tampering - to us by contacting our Support teams. We can help you assess the situation and take the right next steps to protect your business and your customers data.
Recognising a tamper error
Your terminal has triggered tamper protection if you see any of the following:
- A screen reading "PED tampered", "Tamper detected", "Device tampered", "Security error", or "Terminal locked due to tamper".
- A message stating "ALL KEYS HAVE BEEN CLEARED", sometimes followed by a tamper status code and pin reference.
- An instruction to "perform 'clear tamper authority' to recover".
- The terminal stuck in a loop, restarting back into the same tamper screen each time.
- The terminal becomes unusable immediately after being mounted or installed, for example in a kiosk or stand.
What causes a tamper error
Tamper protection usually triggers because of:
- The casing being opened or forced, or broken security seals.
- A drop, knock, or other physical impact.
- Moisture or liquid getting into the device.
- Sustained pressure on the terminal, for example from a tight kiosk enclosure or mounting bracket near the card reader.
What to do next
- Turn the terminal off and don't attempt to open it, reset it, or reinstall any apps. This won't resolve a tamper error and can make diagnosis harder.
- Contact Mollie support with your terminal's serial number, the exact error message shown, and a short description of what happened before the error appeared, including any drops, liquid exposure, or recent installation changes.
- You can install the Mollie Tap app on an iPhone or any Android device to continue processing payments while we assess the situation.
What happens next
Mollie's hardware team will assess whether your terminal needs to be repaired or replaced and get back to you with next steps, normally within 24 hours.