What are you using to serve your main.wasm file?
I don't think it has support for the application/wasm mimetype

You can write your own golang server that can serve your files with a little bit of go:

package main

import (
	"log"
	"net/http"
	"os"
	"strings"
)

func main() {
	if len(os.Args) != 2 {
		log.Fatal("Not enough arguments provided. Please provide the file serving directory.")
	}
	dir := os.Args[1]
	fs := http.FileServer(http.Dir(dir))
	log.Print("Serving " + dir + " on http://localhost:8080")
	http.ListenAndServe(":8080", http.HandlerFunc(func(resp http.ResponseWriter, req *http.Request) {
		log.Println(req.URL)
		resp.Header().Add("Cache-Control", "no-cache")
		if strings.HasSuffix(req.URL.Path, ".wasm") {
			resp.Header().Set("content-type", "application/wasm")
		}
		resp.Header().Set("Access-Control-Allow-Origin", "*")
		fs.ServeHTTP(resp, req)
	}))
}

And then you can run that code with go run main.go [file server directory]

http.FileServer should be serving files with .wasm extension as "application/wasm" since Go 1.11, see commit 534ddf7.

Is it possible your /etc/mime.types or another similar file overrides it to something else?

What does this program print for you? It should be "application/wasm". If not, check your local MIME files(/etc/mime.types, /etc/apache2/mime.types, /etc/apache/mime.types).

@dmitshur, indeed I was expecting the server to automatically recognize and serve as "application/wasm".

Running the mentioned go playground program prints "application/wasm", so there it is working correctly.

A check on /etc/mime.types on my Ubuntu machine (although I never made any adjustments to it) showed application/wasm wasm is not in the list. Also grep 'wasm' /etc/mime.types did not return anything, so I'm sure I did not accidentally overlook it.

I tried by adding the mime type application/wasm wasm to /etc/.mime.types, saved and restarted, however then the error still persists.

@frvannes16, running your example I get the same error in the browser console.

Running the mentioned go playground program prints "application/wasm", so there it is working correctly.

What about if you run the same program on your computer, what does it print then?

Timed out in state WaitingForInfo. Closing.

(I am just a bot, though. Please speak up if this is a mistake or you have the requested information.)