Removed “Convert all links to HTTPS” feature; it has stopped making sense since circa 2015. This was always meant as a simple workaround when Joomla was inserting absolute URLs to images and internal links in the articles, complete with the protocol (http:// or https://), and when third party extensions would include CSS and JS files using absolute URLs always using the http:// protocol. Both of these would cause the site to show a mixed content warning under HTTPS. This feature simply replaced all instances of http:// with https:// in Joomla's output. However, this would also apply to namespaces used in inlined documents, e.g. SVG files, which renders them invalid. In the past 12 years Joomla has stopped storing absolute URLs and third party extensions have stopped using absolute URLs too. This feature has no place but some people still try to use it despite the warning in the documentation about how it works. In an effort to prevent people from shooting their feet we are removing what is essentially a big, mean, foot–gun.
Cannot edit component Options on PHP 8 if the site had Admin Tools 5.1.0 to 5.7.2 installed in the past. Having had at some point Admin Tools 5.1.0 to 5.7.2 inclusive would cause the wrong data type to be stored in the component's Options associated with the “User groups to check for well-known passwords” feature. This was fixed in 5.7.3 and the data was moved to the same storage as the Configure WAF data. However, the old data in the component options was never updated. This didn't cause any problems since this data was not used. That is, until PHP 8 started complaining about the wrong data type being stored in the component's Options. This issue is addressed by removing the no longer used hidden field from the component's Options page.
Please consult our Compatibility page. It explains our version support policy and lists which versions of our software are compatible with which versions of Joomla and PHP.