工作流并发数量是多少?只是并发3个就报错了其中工作流中有迭代节点

调用工作流api执行报错:{“code”:“internal_server_error”,“message”:“The server encountered an internal error and was unable to complete your request. Either the server is overloaded or there is an error in the application.”,“status”:500} ,并发数量3 ,请问该怎么解决呢?