From the announcement at: https://www.php.net/archive/2020.php#2020-11-26-3 

The PHP development team announces the immediate availability of PHP 8.0.0. This release marks the latest major release of the PHP language.

PHP 8.0 comes with numerous improvements and new features such as:

• Union Types
• Named Arguments
• Match Expressions
• Attributes
• Constructor Property Promotion
• Nullsafe Operator
• Weak Maps
• Just In Time Compilation
• And much much more...

Take a look at the PHP 8.0 Announcement Addendum for more information.

For source downloads of PHP 8.0.0 please visit our downloads page, Windows source and binaries can be found on windows.php.net/download/. The list of changes is recorded in the ChangeLog.

The migration guide is available in the PHP Manual. Please consult it for the detailed list of new features and backward incompatible changes.

Many thanks to all the contributors and supporters!

NOTE:

If you want to test XOOPS on PHP 8.0, please use the current code of the upcoming XOOPS 2.5.11 on GitHub: https://github.com/XOOPS/XoopsCore25

If you want to test XOOPS on PHP 8, I just made an "unofficial" Beta 2 version of the upcoming XOOPS 2.5.11

You can download it from: https://github.com/mambax7/XoopsCore25/releases/tag/2.5.11_Beta-2

This is an unofficial release of XOOPS 2.5.11 Beta 2, just to give you a chance to test it on PHP 8

This is a beta release for testing only. Please don't use it in production.

You can always download the latest code for testing from from the current master .

Please download from the current master!

Please help make XOOPS better by testing and reporting any issues!

Any bugs that have been found and fixed will be included in your testing that way, so we all won't keep finding and reporting the same bug over and over.

You can always grab the current master here: https://github.com/XOOPS/XoopsCore25/archive/master.zip