Found the root of the problem !

It was a wrong comparative inside Illuminate\Auth\SessionGuard between values of identifiers.

My identifier is a String of numbers and must be able to have leading zeroes.

Inside my model I have overloaded the getAuthIdentifier() to return the original value which comes from database without converting into integer:

public function getAuthIdentifier(){
        /*
         * Get the original value from database without integer conversion
         */
        return $this->getOriginal('uregistration');
    }

I think there should be an exception when the SessionGuard tries to update the session with the wrong identification. The problem happens here:

https://github.com/laravel/framework/blob/5.3/src/Illuminate/Auth/SessionGuard.php#L443

Thanks !