# 502
source: https://developer.mastercard.com/open-finance-us/documentation/errors/error-codes/502/index.md

This error occurs when the end user session has either expired or timed out.

|             Title             |                                              Details                                              |
|-------------------------------|---------------------------------------------------------------------------------------------------|
| **Aggregation Status Code**   | 502                                                                                               |
| **Remediation Category**      | Invalid Input                                                                                     |
| **HTTP Status**               | 500                                                                                               |
| **Error Type**                | Account Error                                                                                     |
| **Data Connect Alert**        | Internal Server Error. (502)                                                                      |
| **Error Message**             | Invalid function.                                                                                 |
| **Common Causes**             |                                                                                                   |
| **Troubleshooting Steps**     | ​                                                                                                 |
| **Data Connect Fix Eligible** | No.                                                                                               |
| **Retriable by End User**     | No.                                                                                               |
| **Access to Latest Data**     | You will be unable to access the latest data for this user's account until the issue is resolved. |

[Full Error List](https://developer.mastercard.com/open-finance-us/documentation/errors/error-list/index.md)