Since upgrading to 2.3 I now get an error where the font file cannot be found. It is adding /wp-content to the end of the URL instead of after the home domain. This means that the error is only happening on posts, not on the home page.
This looks like something is set up incorrectly on your website.
We’re using a core WordPress function which should grab the URL to your theme folder: get_theme_directory_uri().
In this case, that function is returning the wrong URL.
Can you try:
1. Clearing any caching/minifying plugins you’re using
2. Checking if you’re overwring the WP_CONTENT_DIR or WP_CONTENT_URL constants anywhere (wp-config.php maybe?)
3. If the above doesn’t work, can you try deactivating your plugins one by one to see if one of them is breaking the function?
You can also follow the path as provided from your cpanel and re-upload the file afresh from the theme after you extract it in your computer. Had a similar problem where the woff2 font was missing with the previous version and this issue solved it.