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Mattermost, Inc.

Css style-sheet refused to apply

Summary

Refused to apply style from ‘https://site.example.com/static/main.b2c9393e850ceb701348.css’ because its MIME type (‘text/plain’) is not a supported stylesheet MIME type, and strict MIME checking is enabled.

Steps to reproduce

Upgraded Server from 5.18.1 -> 5.19.2 -> 5.23.0 (Docker Image) - Team Edition

Restore Database, revert to 5.18.1 Image - site loads fine

Expected behavior

Not able to load main page/login

Observed behavior

The resource from “https://site.example.com/static/6.0052dcd4f8d2761e5418.js” was blocked due to MIME type (“text/plain”) mismatch (X-Content-Type-Options: nosniff)

main.26754eebc2bb1ef82024.js:212 Error: Loading CSS chunk 6 failed.
(/static/6.730c6ee7ad669bd95b3c.css)
at HTMLLinkElement.a..a...t.push.a..f.onerror (main.26754eebc2bb1ef82024.js:1)