This section explains the causes and countermeasures for images not displaying, menus (animated child menus) not displaying, and layout collapsing due to style sheet loading failure after SSL conversion.
Why do images not display or layout collapse after SSL (HTTPS)?
Most of the reason for this is because an HTTPS page may be loading HTTP content in the same domain, and the browser may block the loading of content that is not unified to HTTPS.
(The situation where an HTTPS page has HTTP non-encrypted content loading within it is called a mixed content problem.)
In other words, when a page is accessed with HTTPS, if all the loading in the content is also loaded with HTTPS, the aforementioned images not being displayed, menus (child menu animations) not being displayed, style sheets not loading properly, etc. may be resolved.
Where is the mixed content?
The most common places where mixed content is found are in the writing of the theme and in the content recording section of the database.
If you are using an original theme, the loading URL for images and CSS may be written directly into the theme, and if this URL starts with HTTP, it may cause loading failure.
In this case, it is necessary to modify all the following URL writings in the theme to HTTPS.
<link rel="stylesheet" href="http://example.com/aaa.css"> <img src="http://example.com/aaa.jpg">
↓ …
<link rel="stylesheet" href="https://example.com/aaa.css"> <img src="https://example.com/aaa.jpg">
Or you can write the following URL so that it automatically becomes HTTP when loaded over HTTP and HTTPS when loaded over HTTPS.
<link rel="stylesheet" href="//example.com/aaa.css"> <img src="//example.com/aaa.jpg">
Modify the database URL
Rewriting HTTP content written to the database to HTTPS is a difficult manual process, as there may be thousands of them.
or other plug-ins will automatically rewrite the HTTP content to HTTPS after it is read from the database, eliminating the need to rewrite the database.
(It is dangerous to convert the database to HTTPS by issuing SQL statements.
If you rewrite all the HTTP contents in the database by issuing SQL statements at once, you may break the serialized data, and at worst, you may not be able to display the site.
There is a well-known PHP script called Search Replace DB that rewrites the database data at once without destroying the serialized data.
This kind of script is used to rewrite HTTP to HTTPS in bulk.
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