How to fix https problems like "insecure content" or "mixed content" in WordPress

A broken SSL/https webpage (  what is https ? ) can happen when using WordPress. Here are some tips to fix this problem.

In your WordPress admin dashboard

Go to your  WordPress General Settings, in WordPress admin -> Settings -> General 
Your WordPress Address and Site Address has to begin with https.

Fix insecure assets, generally leading to "mixed content" problems

Insecure assets, generally leading to "mixed content" problems must also be retrieved from a https url
You don't need to re-upload all your images of course. You can use the following plugin to help fix this issue in your content.
https://wordpress.org/plugins/ssl-insecure-content-fixer/

For any webpage that still has a "broken lock", after doing the above steps. 
You can use this website to assist in finding the insecure URL 
https://www.whynopadlock.com/


If you use a text widget with custom HTML code for example, make sure that all links are also using https.

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