Illegal Characters in Path Sitecore

Instead of redirecting to the "Item Not Found" page, Sitecore may generate the following error messages when it receives a request containing Illegal characters in the path:

Solution:

I saw a similar issue and it could depend on the "requestPathInvalidCharacters" settings in <httpRuntime> in Web.config.

1. Go to the web.config and search for httpRuntime node.
2. Check if the requestValidationMode is there, if it is not then add the attribute requestValidationMode="2.0" 
3. Make sure validateRequest attribute in the page node is set to false.
   <pages validateRequest="false">
4. If you want to add these characters to the path, add the requestPathInvalidCharacters attribute to the httpRuntime node.
   <httpRuntime targetFramework="4.8" ...... requestPathInvalidCharacters="&lt;,&gt;,*,%,&amp;,:,\,?"/>

Reference:

• Request validation errors

Happy Sitecoreing 😊