Patryk

Force protocol relative (\ instead http:\ or https:\) for files added in the content editor (eg. post, page)
Before, when add media:
<pre><code><a href="https://wordpress.org/wp-content/uploads/some-cool-photo.png"><img src="https://wordpress.org/wp-content/uploads/some-cool-photo.png" alt="Some cool photo" width="1920" height="1410" class="aligncenter size-full wp-image-19200813" /></a>
</code></pre>
After, when add media:
<pre><code><a href="//wordpress.org/wp-content/uploads/some-cool-photo.png"><img src="https://wordpress.org/wp-content/uploads/some-cool-photo.png" alt="Some cool photo" width="1920" height="1410" class="aligncenter size-full wp-image-19200813" /></a>
</code></pre>
The plugin works only for newly added media (does not change the older entries).

PRyC WP: Force protocol relative to uploaded media

Force protocol relative (\ instead http:\ or https:\) for files added in the content editor (eg. post, page)

mohanjith

Code Master

Helps you make the site available via https and http with no effort. Just install and activate 
and say good bye to SSL errors without forcing users to access via http or https only.
<h3>Notes & Credits</h3>
This plugin is written by <a href="http://mohanjith.com/" rel="nofollow ugc">S H Mohanjith</a>.
You should follow us on Twitter <a href="http://twitter.com/codemasteroy" rel="nofollow ugc">here</a>.

WordPress SSL

Have been using this plugin to resolve SSL errors for quite a while.  Has not failed and works just as advertised.  Ensures all links to resources are on the correct protocol.

Has worked well for a long period

Seamlessly map URLs to SSL if the site is accessed via SSL.

PRyC WP: Force protocol relative to uploaded media vs WordPress SSL