while sending base64 or byte[] value the invoke send message method in signalR ,I’m facing Server closed with an error message…

   document.getElementById("sendButton").addEventListener("click", function (event) {
    var user = document.getElementById("username").textContent;
    var message = document.getElementById("messageInput").value;
    var fileInput = document.getElementById("file").value;

    var fileParam = fileInput ? fileInput : null;

    if (message || fileParam) {

                connection.invoke("SendMessage", user, message, fileParam ).catch(function (err) {
                    console.error(err.toString());
                });
        }
        
        document.getElementById("messageInput").value = "";
        fileInput.value = ""; // Clear the file input
    }

document.getElementById("attachments").addEventListener("change", function (event) {
    var file = event.target.files[0];
    var reader = new FileReader();

    reader.onload = function (e) {
        var base64String = e.target.result.split(",")[1];
        document.getElementById("file").value = base64String;
    };

    reader.readAsDataURL(file); 
readAsDataURL
});

I tried with different format of datatype for the processing.I’m expecting to the invoke method successfully accept the base64 format than to Hub class