If you visit YouTube in latest Chrome Canary, you’ll notice the site is broken with page showing gray thumbnails for videos, the reason is this: Google has removed HTML Imports in Canary and if you open developer tools and visit console tab, you’ll notice error informing “HTML Imports is deprecated and will be removed in M73, around March 2019. Please use ES modules instead.” Do note the Only canary is affected, YouTube works fine in other Chrome Channels such as beta, developer and stable as well as in other browsers.
Web Components v0 depreciation and removal
Late year, Google announced it will deprecate and remove web Components v0. In regards to that, Chrome 70 started showing depreciation to users for Custom Elements v0, Shadow DOM v0, and HTML Imports and after all, these are set to be removed in Chrome 73 which will ship on March 12. 2019, which is a week away from today.
You can read more about Web Components depreciation on Polymer project website. YouTube team knows about this change and they’re all well prepared in advance, so you don’t need to worry.
As said by Polymer Project team on twitter, if you’re a developer built your sites with Polymer 1.x or Web Components, be sure to check them in Canary to ensure they are serving polyfills properly. You can follow the discussion about this on this google groups forum thread.
Make Youtube works again in Chrome Canary
If you’re an end user using bleeding edge, you visit YouTube in stable Chrome or run Canary with below command line this is not recommended as it warns Chrome warns as you’re using an unsupported command line flag security and stability will suffer. You can just ignore the warning and watch videos, but the info bar will be displayed at every launch of Chrome browser.
--enable-blink-features=ShadowDOMV0,CustomElementsV0,HTMLImports
March 05, 2019 Update: Chromium team is aware of this and landed a commit to revert this change in Canary, with the next update, you should expect YouTube to work again.
March 06. 2019 Update: Latest update to Canary has fixed the issue.
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The issue is short-lived and fixed within a few days, currently, YouTube is loading fine in Chrome Canary.