500 Internal Server Error when calling RegisterDisplay method in API (

I am experiencing a 500 Internal Server Error when attempting to call the RegisterDisplay method using the following API endpoint:

https://example.com/xmds.php?v=4.1.1&method=RegisterDisplay

I have verified that the method RegisterDisplay should be available in the API as per the provided documentation and the structure of the xmds.php file. However, I am unable to get a successful response, and instead, the server returns a 500 error.

by the way, other apis work successfully for example example.com/api/user/me

I tried the url address I sent the request to with the same result: https://example.com/api/xmds.php?v=4.1.1&method=RegisterDisplay

What should I do?