Today while adding a simple http endpoint to one of our app, I saw this panic: http: multiple registrations with /myhandler. My code was simply

go func(){
	http.Handler("/request", requesthandler)
	http.ListenAndServe(":9000", nil)
}

I read some official documentation and asked around. I came to know it happens if you use defaultHTTPMux, which doesn’t support multiple registrations. This can be fixed with

go func(){
	mux := http.NewServeMux()
	mux.Handler("/request", requesthandler)
	http.ListenAndServe(":9000", nil)
}