The installer shows a blank page or error 500
A PHP extension is usually missing. Ask your host to enable json, simplexml, dom, zlib, gd, zip, mbstring and mysqli.
Why it happens
Joomla needs a handful of PHP extensions. If one is missing, or the PHP version is too old, PHP stops before the installer can show anything.
Fix it
- Check the PHP version in your hosting panel: 8.3+ for Joomla 6, 8.1+ for Joomla 5.
- Make sure these PHP extensions are enabled: json, simplexml, dom, zlib, gd, zip, mbstring and mysqli (or pdo_mysql).
- Look at the server error log in your hosting panel: it names the missing function or extension.
- Reload the installer.
Good to know
- On a VPS, install the missing packages (for example php8.3-xml, php8.3-gd, php8.3-mysql) and restart PHP.
Sources
- Technical Requirements – Joomla Manual
- Unsupported PHP Version – Joomla User Guide
