The URL contains a blocked file or folder name
The “chat” keyword
Live chat scripts are not allowed on InfinityFree hosting. Chat scripts work by constantly refreshing the page in the background. These background refreshes generates excessive server load, which is why we cannot host them. You are free to use live chat on your website though, but you will have to use an externally hosted chat system to handle the messages.
To enforce this, the chat keyword is blocked on our servers. If you try to access any URL with chat in it, you’ll get a 403 Forbidden page. For example, http://example.com/chat.php , http://example.com/livechat/index.php will all result in a 403 error.
To fix this, you can rename the file or folder to anything else (like talk, message, conversation or whatever else you want).