Webform asset javascript (webform/javascript/webform_id/custom.js) is showing not found

Are you saying that the changes in commit 2fc9b78 are what broke this? If you taken 6.3.x and revert that commit, does it fix it?

I have tried with version 6.2.2 and it's working fine. For webform version 6.3.x still an issue.

If you use 6.3.x and revert commit 2fc9b78, does it work?

I can't reproduce this bug in the latest 6.2 release. The JavaScript works for me. So we need improved steps to reproduce.

Oh, I've misread the details here. Let me try again.

I also can't reproduce the bug on 6.3.x.

Having the same issue, strangely enough this only happens on server, dev or production but not locally

I also experienced this issue after upgrading to 6.2.7. The javascript fails to load and I receive a browser error message 'The resource from '.../custom.js' was blocked due to MIME type (“text/html”) mismatch (X-Content-Type-Options: nosniff)." I downgraded to 6.2.4 and received the same error. I then downgraded to 6.2.2 and the javascript loads correctly on that version.

You can use git bisect to figure out which commit was the change that caused this problem.

Thank you for the tip liam. Yes it shows commit 2fc9b78 as the first bad commit for me.

If you take the latest 6.3.x and revert commit 2fc9b78, does that fix it?

Yes, reverting that commit from 6.3.x does get the custom javascript working for me again.

I was having the same problem with css and javascript, I found out that the module fast_404 → was causing the bug, because of the new routing with extension (.ccs, .js).
In my case, uninstalling fast_404 fixed the issue.

I create a patch to revert the code change of css and js asset.

\Drupal\webform\Controller\WebformEntityController::javascript and \Drupal\webform\Controller\WebformEntityController::css are setting the correct content type in the header.

I think we have to keep *.css and *.js extension so that Ajax works as expected.