I wanted to move an EE 4.3.5 website from a development server to a production server.
When I tried to access pages or Control Panel on the production server, the browser displayed a “Disallowed Key Characters” error.
To have more info about the error, at line 997 of system/ee/legacy/core/input.php, I have added the $str variable into the $error variable. The message was then : “Disallowed Key Characters exp_last_visit”. It appears that the error comes frome the “exp_last_visit” value, which is a cookie.
I posted on EE StackExchange : a member suggested to add the cookie_domain and cookie_prefix overrides in my config.php file. But, there is still no result. You can read the discussion here : https://expressionengine.stackexchange.com/questions/40750/disallowed-key-characters-error-when-moving-ee-website-to-another-server
I have migrated several EE2 websites until then and never got this big issue. I suppose something should be done in order to avoid such a blocking error.
ExpressionEngine implements Markdown Extra and BBCode. Please see the Markdown Extra docs and the BBCode Wikipedia article for a full reference.
**bold**, __bold__, *italics*, _italics_, ~strike/del~, `code()`
bold, italics, strike/del, code()
Link: [link title](https://example.com)
Image: 
[blockquote]...[/blockquote], [quote]...[/quote], and Markdown style:
> Some quoted text. > > This is all one quote.
[code]...[/code], and you can also specify the language for syntax highlighting, [code=php]...[/code]
GitHub flavored Markdown code fences are also supported:
```
public function decoderRing($str)
{
return str_rot13($str);
}
```