500 Internal Server Error {“message”:“An unexpected error occurred”}

Hi there, I’m very new to Kong and am currently facing some error. I did the following requests.

Both 1st & 2nd requests returned a 201 response but the third request returned the following

HTTP/1.1 500 Internal Server Error
Date: Wed, 29 Apr 2020 08:32:13 GMT
Content-Type: application/json; charset=utf-8
Connection: keep-alive
Content-Length: 42
X-Kong-Response-Latency: 6
Server: kong/2.0.3

{“message”:“An unexpected error occurred”}

Here is the error log that I have.

2020/04/29 16:32:13 [crit] 8253#0: *100388 connect() failed (22: Invalid argument), context: ngx.timer, client: 127.0.0.1, server: 0.0.0.0:8090
2020/04/29 16:32:13 [crit] 8253#0: *100391 connect() failed (22: Invalid argument), context: ngx.timer, client: 127.0.0.1, server: 0.0.0.0:8090
2020/04/29 16:32:13 [crit] 8253#0: *100394 connect() failed (22: Invalid argument), context: ngx.timer, client: 127.0.0.1, server: 0.0.0.0:8090
2020/04/29 16:32:13 [crit] 8253#0: *100397 connect() failed (22: Invalid argument), context: ngx.timer, client: 127.0.0.1, server: 0.0.0.0:8090
2020/04/29 16:32:13 [crit] 8253#0: *100400 connect() failed (22: Invalid argument), context: ngx.timer, client: 127.0.0.1, server: 0.0.0.0:8090
2020/04/29 16:32:13 [crit] 8253#0: *100403 connect() failed (22: Invalid argument), context: ngx.timer, client: 127.0.0.1, server: 0.0.0.0:8090
2020/04/29 16:32:13 [error] 8253#0: *100387 [lua] balancer.lua:921: execute(): DNS resolution failed: dns lookup pool exceeded retries (1): failed to create a resolver: failed to set peer name: invalid argument. Tried: [“(short)mockbin.org:(na) - cache-miss”,“mockbin.org:33 - cache-miss/scheduled/try 1 error: failed to create a resolver: failed to set peer name: invalid argument/scheduled/try 2 error: failed to create a resolver: failed to set peer name: invalid argument/dns lookup pool exceeded retries (1): failed to create a resolver: failed to set peer name: invalid argument”,“mockbin.org:1 - cache-miss/scheduled/try 1 error: failed to create a resolver: failed to set peer name: invalid argument/scheduled/try 2 error: failed to create a resolver: failed to set peer name: invalid argument/dns lookup pool exceeded retries (1): failed to create a resolver: failed to set peer name: invalid argument”,“mockbin.org:5 - cache-miss/scheduled/try 1 error: failed to create a resolver: failed to set peer name: invalid argument/scheduled/try 2 error: failed to create a resolver: failed to set peer name: invalid argument/dns lookup pool exceeded retries (1): failed to create a resolver: failed to set peer name: invalid argument”], client: 127.0.0.1, server: kong, request: “GET / HTTP/1.1”, host: “example.com

Does anyone know how I can solve this error? Your help is greatly appreciated!