Question on pre and post SSL

I should be using SSL for my website in the present age and there is a question I hope to seek advice here.

Do note the domain name,, used here is fictitious and for example only.

Users use my software to auto login to the password protected registered users area ( to load a text file (file.list) that list the available files to download (a.txt, b.txt, c.txt … and so on). These txt files change from time to time.

The present URLs, I have been using since 1999 are:

The URLs are hard-coded in the software as http.

The protected folder /regusers/ is created via cPanel and it uses .htaccess. I know this may not be the ideal but I hope we leave as it is as my question is in another area, which is:

If I get a SSL for my website, then the above URLs will become https:

After applying the SSL, will there be a problem with the existing software accessing the http URLs (not https) which are hard-coded in the software. I need to manage the migration from non-SSL to SSL. I just changed web-hosting and I see in the cPanel that Let’s Encrypt is available.

Thank in advance.

As long as your set up your server to allow access to http and https (from desktop chrome for example) then there wont be any problem with legacy software doing the same.

When all of your users have migrated, you can then disable http or redirect http to https