Getting odd MIME type check error

[Isaac-Tait]

Summary

My site was running fine then I updated a page (client requested wording nothing else) and now I am getting this error message along with a site loading with zero styling:

Refused to execute script from 'myURL/_next/static/dU0z1bvnjWYdHW3cbAer8/_ssgManifest.js' because its MIME type ('text/html') is not executable, and strict MIME type checking is enabled.

I cleared it the first time by running another build after clearing the cache on the Netlify end. Then a few days later the same error cropped up again (a site with no css and the MIME error message).

Seems like #64350 is having similar issues but only in Lighthouse.

Was there a change in NextJS that is making my site's css no longer discoverable in the directory assets?

Additional information

`Refused` to execute script from 'myURL/_next/static/dU0z1bvnjWYdHW3cbAer8/_ssgManifest.js' because its MIME type ('text/html') is not executable, and strict MIME type checking is enabled.`

Example

No response

[icyJoseph]

I remember someone who had a script, or plugin, which accidentally, transformed CSS files into JavaScript, and IIRC, it would've also done that to JSON files. Let me search around.

[icyJoseph]

So here, #66221 (comment) they had some special webpack config, that was causing CSS to end up as JS scripts. Could it be somewhat similar to your case?

[Joakim-Andersson]

I'm having this same exact issue on a new site. Everything works fine in dev mode, and the site was working fine all week in prod until I updated a small CSS file yesterday. Now, I get 404 & MIME type error. Have you found a solution yet?

[Joakim-Andersson]

Thanks!
I just updated my dependencies and redeployed the site. It worked for about one hour, and then the CSS files went "missing" again. Very frustrating and not sure what to do haha

[Isaac-Tait]

Ugg that is frustrating... I'm worried that is going to pop back up for me too. So, I am definitely invested in trying to figure out what is going on.

Are you using app router or page router?
TailwindCSS or something else?

Could you copy and paste your package.json (mine is below - so we can compare)?

{
  "name": "page_router",
  "version": "0.1.0",
  "private": true,
  "scripts": {
    "dev": "next dev",
    "build": "next build",
    "start": "next start",
    "lint": "next lint"
  },
  "dependencies": {
    "@headlessui/react": "^2.1.2",
    "@heroicons/react": "^1.0.6",
    "@tailwindcss/typography": "^0.5.13",
    "algoliasearch": "^4.24.0",
    "graphql": "^16.9.0",
    "instantsearch.css": "^8.3.0",
    "next": "14.2.5",
    "react": "^18",
    "react-dom": "^18",
    "react-instantsearch": "^7.12.2",
    "react-instantsearch-dom": "^6.40.4",
    "react-instantsearch-router-nextjs": "^7.12.2",
    "tailwindcss-hero-patterns": "^0.1.2"
  },
  "devDependencies": {
    "autoprefixer": "^10.4.19",
    "eslint": "^8.57.0",
    "eslint-config-next": "14.2.5",
    "postcss": "^8",
    "tailwindcss": "^3.4.7"
  },
  "comments": {
    "dependencies": "@heroicons/react should not be upgraded to v2 or else it will cause the mobile menu to return an error"
  }
}

[icyJoseph]

When this error happens, is it a 404 that's returned for the script? with a full HTML page on it?

[icyJoseph]

Found this thread elsewhere, https://answers.netlify.com/t/intermittent-404-errors-and-inconsistent-page-loads-on-next-js-app-hosted-on-netlify/96997/12 any change it is somewhat related?

[Isaac-Tait]

My app is hosted on Netlify... and yes it was throwing a 404 error in conjunction with the MIME error. Maybe @Joakim-Andersson can upload a screenshot? My app isn't currently erroring out.

Great sleuthing @icyJoseph 🫡

[Isaac-Tait]

That issue has since been closed (13 hours ago as of this posting) and re-directed to this one:
https://answers.netlify.com/t/javascript-bundle-issues-netlify-build-breaking-several-hours-after-deployment-completes/122901/2

[Isaac-Tait]

It might be resolved - Netlify released a patch. If you redeploy and purge the cache you should be good to go 🤞🏼
https://answers.netlify.com/t/javascript-bundle-issues-netlify-build-breaking-several-hours-after-deployment-completes/122901/50?u=isaac-tait

[ALFAMAS]

is there any fix
cause i am running on latest version but mines still facing same issue with CI/CD