Validate html error when enable critical css

[minhluan259]

Preconditions (*)

1. Magento 2.3.4

Steps to reproduce (*)

1. Enable Critial CSS
2. Validate html https://validator.w3.org/

Expected result (*)

1. Validate html without error

Actual result (*)

1. Validate html error
   https://prnt.sc/qz5dz9

magento2/app/code/Magento/Theme/Controller/Result/AsyncCssPlugin.php

Lines 60 to 66 in 9544fb2

	$loadCssAsync = sprintf(
	'<link rel="preload" as="style" media="%s" .
	onload="this.onload=null;this.rel=\'stylesheet\'"' .
	'href="%s">',
	$media,
	$href
	);

need change to

                    $loadCssAsync = sprintf(
                        '<link rel="preload" as="style" media="%s" 
                         onload="this.onload=null;this.rel=\'stylesheet\'"' .
                        ' href="%s">',
                        $media,
                        $href
                    );

[m2-assistant]

Hi @minhluan259. Thank you for your report.
To help us process this issue please make sure that you provided the following information:

• Summary of the issue
• Information on your environment
• Steps to reproduce
• Expected and actual results

Please make sure that the issue is reproducible on the vanilla Magento instance following Steps to reproduce. To deploy vanilla Magento instance on our environment, please, add a comment to the issue:

@magento give me 2.4-develop instance - upcoming 2.4.x release

For more details, please, review the Magento Contributor Assistant documentation.

@minhluan259 do you confirm that you were able to reproduce the issue on vanilla Magento instance following steps to reproduce?

• yes
• no

---

• Join Magento Community Engineering Slack and ask your questions in #github channel.

[magento-engcom-team]

✅ Confirmed by @sudheers-kensium
Thank you for verifying the issue. Based on the provided information internal tickets MC-31378 were created

Issue Available: @sudheers-kensium, You will be automatically unassigned. Contributors/Maintainers can claim this issue to continue. To reclaim and continue work, reassign the ticket to yourself.

[magento-engcom-team]

Hi @minhluan259. Thank you for your report.
The issue has been fixed in #26764 by @srsathish92 in 2.4-develop branch
Related commit(s):

• f9697f509ae09f5c9e0f0d7b1a2de7ed9a53fc16
• bf21c4bea3cbd600ee1333186bf43b3065847681
• 2881e4886fee787e5ecdf73edef4a197321bea43
• 1e50859a6c2f52984a9a2812fb6c93aa6b0a0f34

The fix will be available with the upcoming 2.4.0 release.