Upon launching an Angular application on Heroku, a situation arises where accessing the URL displays a blank page and the console reveals MIME type errors.
The error message reads:
"Failed to load module script: The server responded with a non-JavaScript MIME type of 'text/html'. Strict MIME type checking is enforced for module scripts per HTML spec."
Here's a likely reason for the issue:
This problem may occur if you deploy your application in a subdirectory instead of at the root URL.
What's happening:
www.yourbase.com/yoursubfolder/index.htmlwww.yourbase.com/resource.css instead of www.yourbase.com/yoursubfolder/resource.csswww.yourbase.com/resource.css (possibly your www.yourbase.com/index.html)Solution:
Build your Angular app with
ng build --prod --base-href yoursubfolder
Or specify the base path in your index.html file
<head>
<base href="/yoursubfolder/">
</head>
Encountered the same issue while trying to deploy an Angular UI in a subfolder of nginx.
After some troubleshooting, I managed to resolve it. Sharing my solution here.
For example, if you wish to host your website at
Step 1: Use --base-href when building
ng build --base-href=/sub1/
Step 2: Nginx configuration
There are two approaches to hosting your subfolder.
Assuming your dist folder is located at html/sub1dist
1) Hosting local dist as a subfolder
server {
listen 80;
server_name localhost;
location /sub1 {
alias html/sub1dist;
try_files $uri $uri/ /index.html =404;
}
}
2) Proxy passing another endpoint as a subfolder
server {
listen 80;
server_name localhost;
location /sub1/ {
# rewrite to remove the subfolder
rewrite ^/sub1/(.*)$ /$1 break;
proxy_pass http://127.0.0.1:8071;
}
}
server {
listen 8071;
server_name localhost;
location / {
root html/sub1dist;
try_files $uri $uri/ /index.html =404;
}
}
Both of the above solutions have worked successfully for me.
The issue I encountered was identical. It turned out to be a problem with the express server.js file.
app.use(express.static(__dirname + '/dist/<app-folder-name>'));
// PathLocationStrategy
app.get('/*', function(req, res) {
res.sendFile(path.join(__dirname + '/dist/<app-folder-name>/index.html'));
})
If you forget to specify your app-folder-name after the dist folder in the express.static method, it will lead to a MIME type error as it won't be able to locate your Javascript bundles.
I recommend giving this a try as it was successful for me
"server": {
"builder": "@angular-devkit/build-angular:server",
"options": {
"outputPath": "dist/server",
Make the following adjustment:
"outputPath": "dist/",
Consider implementing the X-Content-Type-Options header with the 'nosniff' attribute on your server.
Essentially, MIME (Multipurpose Internet Mail Extensions) helps browsers automatically determine if the content type being sent is appropriate for the application. By using this header and attribute, you are essentially telling the server that you have everything under control, which should help eliminate MIME errors.
For more information on X-Content-Type-Options, check out the resources provided by Mozilla:
https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Content-Type-Options
Here is a working solution for using Angular8 with Express:
app.use('/', express.static('classvideo'));
app.get('*', (req,res,next) => {
const indexFile = path.resolve(__dirname + '/classvideo/index.html');
res.sendFile(indexFile);
});
When working with .NET Core 3.1, ensure that you have added app.UseSpaStaticFiles(); in the Startup.cs file.
Ensure consistency by deploying the same build across all load-balanced servers.
If you are utilizing load balancing during deployment and only updating one server, it can result in multiple versions of the deployment being active simultaneously.
Due to the nature of load balancing, when a browser tries to resolve file paths in the index.html, it may end up accessing different servers with varying file versions. This can lead to missing files pointing back to the index.html itself, causing issues with module loading.
When trying to publish my Angular 9 application on an IIS 8 server, I encountered a problem that only occurred on the customer's machine. The issue stemmed from how the application was published - on my machine, I specified the baseRef to be within a folder called myFolder in the Site, while the customer created a new site directly pointing to the folder without creating it within an existing site.
The solution for me was to generate the publish without specifying the baseRef (using ng build --prod). Essentially, the error arose from the server being unable to locate the project files based on how they were compiled.
In my situation, it turned out to be a server-side issue that needed addressing. After implementing some rewriting techniques, the problem was resolved successfully. I found that by including the following code in the .htaccess file, everything worked flawlessly.
<IfModule mod_rewrite.c>
RewriteEngine on
RewriteCond %{HTTPS} off
RewriteRule (.*) https://%{HTTP_HOST}%{REQUEST_URI} [R,L]
# Avoid rewriting files or directories
RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ - [L]
# Redirect all other requests to index.html
# for supporting html5 state links
RewriteRule ^ index.html [L]
</IfModule>
Once I cleared the browser cache, the website began loading without any issues.
I encountered a similar issue while attempting to deploy on render.com
The problem might be related to an incorrect resolution of the path. Please see the code below for a possible solution.
// serving static assets in production
if (process.env.NODE_ENV === 'production') {
const staticPath = path.resolve(__dirname, '../../', 'client', 'dist');
// setting up a static folder
app.use(express.static(staticPath));
// delivering index.html
app.get('*', (req, res) => {
res.sendFile(path.resolve(staticPath, 'index.html'));
});
}
I encountered a similar issue when working with Angular 15 and deploying on Azure app service.
This particular error tends to occur when the server is serving JavaScript files with an incorrect MIME type.
The solution to this problem involves configuring the MIME types in your (Azure) deployment settings.
<?xml version="1.0"?>
<configuration>
<system.webServer>
<staticContent>
<clientCache cacheControlCustom="public" cacheControlMode="UseMaxAge" cacheControlMaxAge="365.00:00:00" />
<remove fileExtension=".json" />
<remove fileExtension=".woff" />
<remove fileExtension=".woff2" />
<remove fileExtension=".js" />
<mimeMap fileExtension=".json" mimeType="application/json" />
<mimeMap fileExtension=".woff" mimeType="application/x-font-woff" />
<mimeMap fileExtension=".woff2" mimeType="application/font-woff2" />
<mimeMap fileExtension=".js" mimeType="application/javascript" />
</staticContent>
<rewrite>
<rules>
<rule name="Angular4" stopProcessing="true">
<match url=".*" />
<conditions logicalGrouping="MatchAll">
<add input="{REQUEST_FILENAME}" matchType="IsFile" negate="true" />
<add input="{REQUEST_FILENAME}" matchType="IsDirectory" negate="true" />
</conditions>
<action type="Rewrite" url="/" />
</rule>
</rules>
</rewrite>
</system.webServer>
</configuration>
By implementing this configuration, you can ensure that the specified file extensions are served with the correct MIME types.
If the issue persists, remember to clear your browser cache before retesting, as the incorrect MIME type may be cached by your browser.
It's important to note that the resolution for this error involves the following steps:
<?xml version="1.0" encoding="UTF-8"?>
<configuration>
<system.webServer>
<staticContent>
<remove fileExtension=".js" />
<mimeMap fileExtension=".js" mimeType="application/javascript" />
</staticContent>
</system.webServer>
</configuration>
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