What could be the reason for class_exists() always returning false when checking for a class with a specific namespace?

The reason for class_exists() always returning false when checking for a class with a specific namespace could be due to the namespace not being correctly specified in the class name parameter. To solve this issue, make sure to include the full namespace when checking for the class existence.

// Incorrect way of checking for class existence without specifying the namespace
$classExists = class_exists('MyClass');

// Correct way of checking for class existence with the full namespace specified
$classExists = class_exists('MyNamespace\\MyClass');