# S03039 {#s03039}

## Error Code {#error_code .section}

S03039

## Error Message {#error_message .section}

`Failed to serialize events due to incompatible event fields. Expected: <xxx>. Actual: <xxx>. RefId: S03039`

## Probable Causes {#probable_causes .section}

This error occurs when the number of fields in the event passed does not match the the number of eventField defined in the *eventSchema* of `StreamEventSerializer`.

## Solutions {#solutions .section}

Check whether the event type passed matches the `eventSchema` defined in the `StreamEventSerializer`.

**Parent topic:**[Error Code Reference](../../Troubleshooting/ErrorCode.md)

