Fatal error when Gravity PDF runs alongside another plugin that bundles Monolog 3 / PSR-Log v3 (e.g. WP-Stateless)

[grogou]

Environment

Gravity PDF: 6.14.2 (also reproduced on 6.13.5)
WP-Stateless: 4.4.1 (bundles Monolog 3.x + PSR/Log v3)
WordPress: latest
PHP: 8.3.26

Error

Fatal error: Declaration of Monolog\Logger::emergency(Stringable|string $message, array $context = []): void must be compatible with GFPDF_Vendor\Psr\Log\LoggerInterface::emergency($message, array $context = []) in /wp-content/plugins/wp-stateless/lib/Google/vendor/monolog/monolog/src/Monolog/Logger.php on line 683

Reproduction

Install Gravity PDF 6.14.2 + WP-Stateless 4.4.1 (or any plugin shipping Monolog 3 / PSR/Log v3).
Trigger any code path that boots WP-Stateless's Google client (image upload, GCS sync, cron). This lazy-loads wp-stateless/lib/Google/vendor/autoload.php.
Backend fatals.

Root cause

Gravity PDF's PSR/Log compatibility shim in src/Helper/Log/Logger.php::get_monolog() decides the PSR/Log version at first call by running trait_exists('\Psr\Log\LoggerTrait'). WP-Stateless registers its v3 Psr\Log\ autoloader lazily (only when the Google client is instantiated), so on first call from Gravity PDF the trait isn't registered yet → shim falls into the v1 branch and runs:

class_alias( '\GFPDF_Vendor\Psr\Log\LoggerInterface', '\Psr\Log\LoggerInterface' );
This permanently binds the global \Psr\Log\LoggerInterface to the v1 signature. Later, when WP-Stateless boots its bundled Monolog 3, PHP rejects Monolog\Logger::emergency(string|\Stringable $message): void against the aliased v1 signature.

A second, structural issue: in vendor_prefixed/monolog/src/Monolog/Logger.php (and ~28 other files inside vendor_prefixed/), the \Psr\Log\ namespace was not prefixed by the build tool, e.g.:

class Logger implements \Psr\Log\LoggerInterface, \GFPDF_Vendor\Monolog\ResettableInterface
So Gravity PDF's own prefixed Monolog still depends on the global \Psr\Log\LoggerInterface resolving to v1, which is why vendor/psr/log/ still ships an unprefixed v1 alongside vendor_prefixed/psr/log/.

The result is that class_alias is needed every time another plugin loads PSR/Log v3 lazily after Gravity PDF has booted — and the compat shim's trait_exists check is a race against lazy autoloaders.

Suggested fix (one or more)

Replace trait_exists snapshot with an autoload-aware probe, or defer get_monolog() until plugins_loaded priority near PHP_INT_MAX so lazy autoloaders have registered.
Prefix every \Psr\Log\… reference inside vendor_prefixed/ so Gravity PDF's prefixed Monolog implements \GFPDF_Vendor\Psr\Log\LoggerInterface. Then drop the unprefixed vendor/psr/log/ ship and the global class_alias entirely.
Provide a filter or constant (e.g. GFPDF_FORCE_PSR_LOG_VERSION) so site owners can pin the target version when load-order detection is unreliable.

[jakejackson1]

Thanks for reporting this issue.

Gravity PDF's PSR/Log compatibility shim in src/Helper/Log/Logger.php::get_monolog() decides the PSR/Log version at first call by running trait_exists('\Psr\Log\LoggerTrait'). WP-Stateless registers its v3 Psr\Log\ autoloader lazily (only when the Google client is instantiated), so on first call from Gravity PDF the trait isn't registered yet → shim falls into the v1 branch and runs:

If you add the following code to your site the WP-Stateless plugin and Gravity PDF will play nice together:

add_action( 'plugins_loaded', function () {
	if ( function_exists( 'ud_get_stateless_media' ) ) {
		include_once( ud_get_stateless_media()->path( 'lib/Google/vendor/autoload.php', 'dir' ) );
	}
} );

That ensures the PSRv3 library included in WP-Stateless is loaded before Gravity PDF's PSR shim, and the shim will be able to function correctly.

A second, structural issue: in vendor_prefixed/monolog/src/Monolog/Logger.php (and ~28 other files inside vendor_prefixed/), the \Psr\Log\ namespace was not prefixed by the build tool,

This was intentional for backwards compatibility reasons. The work for the shim allows our version of Monolog to run with any version of PSR Log (1/2/3).

Prefix every \Psr\Log\… reference inside vendor_prefixed/ so Gravity PDF's prefixed Monolog implements \GFPDF_Vendor\Psr\Log\LoggerInterface. Then drop the unprefixed vendor/psr/log/ ship and the global class_alias entirely.

Isolating all vendor files under our own namespace is our end goal. Because it's a breaking change, the next major version of Gravity PDF (v7.0) will include this update. The shim is a temporary stop gap solution that works in most circumstances (provided a plugin doesn't lazy load their composer autoloader).