CodeIgniter error Disallowed Key Characters

Good afternoon.

When integrating a script into CodeIgniter framefork, the whole site is blocked and the Disallowed Key Characters error is displayed. Some kind of framework protection? How to bypass it? And how to restore the site?

Working with form, post method

CSRF protection? See Manual for Filters

If you are not a bot, I recommend to upgrade to CodeIgniter 4.
Sorry if you are a human, there are a lot of posts by bots in this forums.

The error message "Disallowed Key Characters" is not in CI3 or 4.
It was probably in CI2.

ci-phpunit-test | CodeIgniter Testing Guide | CodeIgniter 3 to 4 Upgrade Helper

If you are not a bot, I recommend to upgrade to CodeIgniter 4.
Sorry if you are a human, there are a lot of posts by bots in this forums.

The error message "Disallowed Key Characters" is not in CI3 or 4.
It was probably in CI2.

So, my old site on CodeIgniter 2, I don't know how to programming, so I can't upgrade to the new version of CodeIgniter. I thank you on the Internet, I found a way out for whoever needs it, I will leave it here. 

application/config/config.php

PHP Code:

$config['permitted_uri_chars'] = 'a-z 0-9~%.:_\-';

system/core/Input.php 


PHP Code:

if ( ! preg_match("/^[a-z0-9:_\/-]+$/i", $str))
{
  exit('Disallowed Key Characters.');
}

or
if ( ! preg_match("/^[a-z0-9:_\/-=]+$/i", $str))
{
  exit('Disallowed Key Characters.'. $str);
}

}