You need to do something like this to clear it:
while(openssl_error_string() !== false);
Some openssl functions will add errors to the list even if they succeed.
(PHP 4 >= 4.0.6, PHP 5, PHP 7, PHP 8)
openssl_error_string — Return openSSL error message
openssl_error_string() returns the last error from the openSSL library. Error messages are queued, so this function should be called multiple times to collect all of the information. The last error will be the most recent one.
Esta função não possui parâmetros.
Returns an error message string, or false if there are no more error
messages to return.
Exemplo #1 openssl_error_string() example
<?php
// lets assume you just called an openssl function that failed
while ($msg = openssl_error_string())
echo $msg . "<br />\n";
?>