500 (Internal Server Error)

I had CORS issue and added proxy to ionic.config.json
Now I get this error

{"headers":{"normalizedNames":{},"lazyUpdate":null},"status":500,"statusText":"Internal Server Error","url":"http://localhost:8100/api","ok":false,"name":"HttpErrorResponse","message":"Http failure response for http://localhost:8100/api: 500 Internal Server Error","error":"<!DOCTYPE html>\n<html lang=\"en\">\n<head>\n<meta charset=\"utf-8\">\n<title>Error</title>\n</head>\n<body>\n<pre>Error: getaddrinfo ENOTFOUND myurl.com myurl.com:443<br> &nbsp; &nbsp;at GetAddrInfoReqWrap.onlookup [as oncomplete] (dns.js:57:26)</pre>\n</body>\n</html>\n"}

Here is the link to my post
What does this error mean and what can I do to rectify it?