Intermittent: Browser refuses CSS/JS static files due to incorrect mime type text/plain

For the last couple of day my users are reporting occasional errors where the browser refuses to accept both CSS and JS due to Netlify returning them with mime type text/plain. I confirmed with on the command-line with the httpie tool.

This site has been up for 9+ months and the last deploy has been running fine since mid-December without issue. Yesterday the issue persisted through a “Clear cache and deploy site”, then mysteriously went away after a few hours.

Today users are complaining about the issue once again although I cannot reproduce it myself. Netlify, what is going on?

In an attempt to kick the system I’ve made a tiny change to the site today (which is SvelteKit) to switch from Edge functions back to regular ones, but given the issue applies to static files I seriously doubt it will have any impact.

(site is on the Netlify account of my collaborator, but I’m the technical contact)

This sounds like related to: Netlify server crashes site because of wrong mime/types - #4 by hrishikesh

Please post any follow-ups in the original thread.