SSL on 4.2.x
 

If you install an SSL certificate on a vB board will it end up showing broken on threads?

No, the reason they'll show a broken SSL cert on any page, is for hard linked images & off site images etc...

You'll need to use the dev console in the browser & see what images etc arent coded with https, you can use htaccess to fix them as well, but that isnt the correct way of doing it, as that is eating up server resources for all the non-needed rewrite of the images.

That is basically what I am asking, is vB by nature going to display non-SSL images, etc. and make posts/threads unsecure?

You could proxy the images - https://vborg.vbsupport.ru/showthread.php?t=288060 (I didn't like this myself).

Tbh as most servers now are https enabled and most modern browsers support it the easy way is just to add a upgrade-insecure-requests header and the browser will grab the https version, this is all I do on my sites and never have any problems.

Add to your headerincludes template

What we did to get around the hard link images and to eliminate the threads being broken should the images be removed was to install:

https://vborg.vbsupport.ru/showthread.php?t=253309

I also found a few addons that made calls and or placed invisible images in the footer for tracking/copyright purposes. These were easily identified in the log files and, eradicated accordingly.