xmlHttpRequest.open("GET",url,true); Uncaught TypeError: Cannot read properties of undefined (reading 'open')

This error is thrown when the "open" method of the XMLHttpRequest object is called on an undefined object. This can happen if the object has not been created properly, or if the code is attempting to access the object before it has been fully loaded.

To fix this error, make sure that the XMLHttpRequest object is created and initialized properly before calling the "open" method. Also ensure that the URL parameter passed to the "open" method is valid and points to the correct resource.