in awslambdaric/lambda_runtime_client.py [0:0]
def post_invocation_error(self, invoke_id, error_response_data, xray_fault):
max_header_size = 1024 * 1024 # 1MiB
xray_fault = xray_fault if len(xray_fault.encode()) < max_header_size else ""
runtime_client.post_error(invoke_id, error_response_data, xray_fault)