HTTPS website has assets that are called using plain HTTP to the same domain because of the mixed content problem

[mr-elamin]

Hi Classroombookings Developer,

I started using Classroombookings just two days ago and everything under HTTP on port 80 is working perfectly and very quickly.
however, after I copied and configured apache2 default-ssl.conf to use my let's encrypt SSL Certificate, the site is not loading correctly under the port 443 HTTPS.
please check it in here:
https://classroombookings.try-my-app.com/index.php/login

my browser is reporting:

"This site has a valid certificate, issued by a trusted authority.
However, some parts of the site are not secure. This means information (such as passwords or credit cards) might not be securely sent to this site and may be intercepted or seen by others."

I have about zero experience in PHP programming but after a long search on the internet I found similar issues like this and the blogger reporting this problem due to HTTPS website with assets that are called using plain HTTP to the same domain because of the mixed content

I'd suspect there's something in the page code that is making an http:// call instead of an https:// call, so I believe something must have changed in the source code, but I don't know what's that, could anyone help with this issue?
Thanks a lot!

[mr-elamin]

I had the same problem with my WordPress Websites, but after adding this line of code:

// force SSL
$_SERVER['HTTPS']='on';

in the "wp-config.php" file the problem was resolved.

[mr-elamin]

Finally, I found the solution here!
https://www.edugeek.net/forums/educational-software/221391-classroom-bookings-software.html

just by changing the local/config.php and replacing the:
'base_url' => 'http://example.com/classroombookings/',
with
'base_url' => 'https://example.com/classroombookings/',

after that, everything worked perfectly!