PHP-GMP-001
optional
PHP gmp extension (WebAuthn)
Joomla 4+ WebAuthn/passkeys need GMP. Upgrades fail or MFA breaks without it.
optional → Enable ext-gmp on PHP 8.1+
What you will see
- Class "GMP" not found
- gmp_init()
Symptoms people search
passkey error · webauthn · gmp
Replace this code
Swap optional for Enable ext-gmp on PHP 8.1+.
Joomla 3
Remove or stop calling this
// Joomla 3 sites often omitted gmpJoomla 4 / 6
Use this instead
php.ini: extension=gmp (required for passkeys / WebAuthn on many J4+ hosts)How to fix it
- 1Enable gmp (and sodium/openssl).
- 2Confirm with phpinfo on staging.
Also known as
gmp · WebAuthn · passkeys
Related issues
- Joomla 3 → 4PHP
jimport() autoloader calls
jimport('joomla.filesystem.file') → use Joomla\CMS\Filesystem\File;
- Joomla 3 → 4PHP
DS path constant
DS → DIRECTORY_SEPARATOR or /
- Joomla 3 → 4PHP
JPATH_PLATFORM
JPATH_PLATFORM → Do not use — autoload instead
- Joomla 3 → 4PHP
mysql_* PHP functions
mysql_query() → Joomla DatabaseInterface / mysqli / PDO
- Joomla 3 → 4PHP
each() / create_function() / ereg / split
each($array) → foreach / closures / preg_*
- Joomla 4 → 5PHP
Dynamic PHP properties (PHP 8.2+)
$this->foo = 1 on an untyped class → Declare the property or use AllowDynamicProperties