After upgrading to Angular 8, production builds can't load: Failed to load module script: The server responded with a non-JavaScript MIME type of "text/plain". Strict MIME type checking is enforced for module scripts per HTML spec.

🐞 bug report

Affected Package Angular 8

Is this a regression? YES

Description

My production distribution is being served from Azure Blob Storage static site. Is it possible that serving from the static site is causing this error?

This issue happens in Chrome but not Edge.

After upgrading to Angular 8, production builds can’t load. Browser console error: Failed to load module script: The server responded with a non-JavaScript MIME type of “text/plain”. Strict MIME type checking is enforced for module scripts per HTML spec.

🔬 Minimal Reproduction

Upgrade an Angular 7 app to Angular 8. Do production build, deploy the production build to Azure Blob storage static web site and attempt to open it.

🔥 Exception or Error

Failed to load module script: The server responded with a non-JavaScript MIME type of "text/plain". Strict MIME type checking is enforced for module scripts per HTML spec.

🌍 Your Environment

Angular Version:

Angular CLI: 8.0.1
Node: 11.6.0
OS: win32 x64
Angular: 8.0.0
... animations, common, compiler, compiler-cli, core, forms
... language-service, platform-browser, platform-browser-dynamic
... router

Package                           Version
-----------------------------------------------------------
@angular-devkit/architect         0.800.1
@angular-devkit/build-angular     0.800.1
@angular-devkit/build-optimizer   0.800.1
@angular-devkit/build-webpack     0.800.1
@angular-devkit/core              8.0.1
@angular-devkit/schematics        8.0.1
@angular/cdk                      7.3.7
@angular/cli                      8.0.1
@angular/material                 7.3.7
@ngtools/webpack                  8.0.1
@schematics/angular               8.0.1
@schematics/update                0.800.1
rxjs                              6.5.2
typescript                        3.4.5
webpack                           4.30.0

[btey]

You must change the property “target” in the file “tsconfig.json” to “es5”. Read this blog entry, “Differential Loading by Default”:

https://blog.angular.io/version-8-of-angular-smaller-bundles-cli-apis-and-alignment-with-the-ecosystem-af0261112a27

This property chooses between modern or legacy JavaScript based on the browser capabilities:

<script type="module" src="…"> // Modern JS

<script nomodule src="…"> // Legacy JS

[alan-agius4]

Hello, we reviewed this issue and determined that it doesn’t fall into the bug report or feature request category. This issue tracker is not suitable for support requests, please repost your issue on StackOverflow using tag angular-cli.

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