Diagnosing intermittent 502 Bad Gateway errors on Worldline card terminals in a retail setting. Troubleshooting network connectivity, cable issues, and ESD.
Record how often the errors occur to help identify patterns or triggers.
Determine if the issue is isolated to the terminal or a wider network problem.
Recent changes might be the source of the problem.
A 502 Bad Gateway error indicates the terminal's request to a server (likely processing payment authorization) failed because the server received an invalid response. This can be caused by network connectivity issues, server-side problems, or issues with the terminal's communication module. Key areas of concern include: Voltage fluctuations impacting network card stability, signal attenuation within the network cable, baud rate mismatch (unlikely but possible), or transient ESD events disrupting data transmission during card swipes.
Do not attempt to open the terminal casing. These devices contain anti-tamper mechanisms. Opening the device will void the warranty and may render it unusable. Static electricity can damage electronic components. Avoid touching the terminal's connectors directly, especially in dry conditions. No Lockout/Tagout (LOTO) is required as the maintenance is external; adhere to Safe Handling procedures (unplugging the power supply).
Regularly inspect network cables for damage and ensure secure connections. Provide adequate strain relief for cables to prevent damage from bending or pulling. Clean the touchscreen with a soft, dry cloth to remove debris. In dry environments, consider using anti-static mats to minimize ESD.
If using a wired Ethernet connection, temporarily try connecting the terminal to a different port on the network switch/router to rule out a faulty port. Note the date and time of occurrence when reporting failures to Worldline support for log correlation.