cast_sender.js error: Failed to load resource: net::ERR_FAILED in Chrome

Question

I recently started receiving the following console errors, without any code changes taking place.

I did not install any extensions recently.

Failed to load resource: net::ERR_FAILED chrome-extension://enhhojjnijigcajfphajepfemndkmdlo/cast_sender.js
Failed to load resource: net::ERR_FAILED chrome-extension://hfaagokkkhdbgiakmmlclaapfelnkoah/cast_sender.js
Failed to load resource: net::ERR_FAILED chrome-extension://enhhojjnijigcajfphajepfemndkmdlo/cast_sender.js
Failed to load resource: net::ERR_FAILED chrome-extension://fmfcbgogabcbclcofgocippekhfcmgfj/cast_sender.js
Failed to load resource: net::ERR_FAILED

I have several YouTube player embeds on the page that are triggering this error, but they are simple:

<iframe width="100%" height="100%" src="http://www.youtube.com/embed/OUR_YOUTUBE_ID?showinfo=0&amp;wmode=transparent" frameborder="0" allowfullscreen=""></iframe>

Has anybody else experienced this?

Answer 1

Apparently YouTube constantly polls for Google Cast scripts even if the extension isn't installed.

From one commenter:

... it appears that Chrome attempts to get cast_sender.js on pages that have YouTube content. I'm guessing when Chrome sees media that it can stream it attempts to access the Chromecast extension. When the extension isn't present, the error is thrown.

Read more

The only solution I've come across is to install the Google Cast extension, whether you need it or not. You may then hide the toolbar button.

For more information and updates, see this SO question. Here's the official issue.