500 error when adding nodes

[mcai2]

Login is fine, ping pong test is fine too, but when I tried to add new node, it shows 500 error

HTTP/1.1 500 Internal Server Error
X-Powered-By: Express
Content-Type: application/json; charset=utf-8
Content-Length: 12
ETag: W/"c-3Rk1bge0s6VuJbi+S2m2iU0UGdY"
Date: Tue, 17 Sep 2019 10:03:35 GMT
Connection: keep-alive

[DearTanker]

Same Problem.