I've been grappling with this bug over several days now to no luck. When editing either a post or a page, all icons in the Visual Editor are missing:
As you can see this, includes the icon for the Gutenberg Add Block, which is completely invisible and here highlighted by its alt text. Also notice that the icons in the WP Admin section/toolbar display as normal, indicating the problem is only with the icons of the Visual Editor.
What I've Tried
To date, my extensive Googling, tweaking and testing has proved useless. The following is a list of all the solutions I've tried so far, from the standard to the slightly more complex:
Clearing browser cache/viewing the page in private browsing mode (as suggested here)
Deactivating all plugins (as suggested here)
Checking that the values of Wordpress Address and Site Address in
Settings > Generalmatch
Settings > Permalinksand clicking Save Changes (as suggested here)
define( 'WP_MEMORY_LIMIT', '96M' );to wp-config
define( 'WP_MAX_MEMORY_LIMIT', '256M' );to wp-config
define(‘CONCATENATE_SCRIPTS’, false);to wp-config (as suggested here)
$_SERVER[“HTTPS”] = “on”;to wp-config (as suggested here)
wp-includes/js/TinyMCEfolder entirely with the same folder from a fresh Wordpress download (as suggested here)
Replacing the entirety of
wp-adminwith the same folder from a fresh Wordpress download (as suggested here)
wp-clito do a site-wide search-and-replace of
https://www.myexamplesite.com(as suggested here)
Disabling both HTTPS Enforce and and External Links Rewrite in using Siteground's cPanel (but not deleting the SSL certificate itself)
Not a single one of the above solutions results in the icons being restored again, even when I check the changes using Incognito/Private Browsing to counteract caching.
I have some suspicion that this issue could have been caused by activating free Let's Encrypt SSL on the server, due to this post, and I also don't recall this issue occurring before I made that change, but I'm unsure as to a) how exactly enabling the free Let's Encrypt SSL would cause such an issue, and b) how it would be fixed.
Has anyone else dealt with this before?