Getting Unexpected response data from server when I try to update my txt file

I am creating a text file and saving data in it but when I try to update this file than I am getting following error

Unexpected response data from server.

My Code is

function SetupTenantInfo() {

    var siteURL = window.location.href.split("/Pages/Config.aspx");
    var clientContext = new SP.ClientContext(siteURL[0]);
    //parentWeb = parentCtx.get_web();
    scriptList = clientContext.get_web().get_lists().getByTitle("Document");

    fileCreateInfo = new SP.FileCreationInformation();
    fileCreateInfo.set_url("Info.txt");
    fileCreateInfo.set_overwrite(true);
    fileCreateInfo.set_content(new SP.Base64EncodedByteArray());

    // Read the binary contents of the base 64 data URL into a Uint8Array
    // Append the contents of this array to the SP.FileCreationInformation
    var arr = str2ab(tenantInfo);//convertDataURIToBinary(result);
    for (var i = 0; i < arr.length; ++i) {
        fileCreateInfo.get_content().append(arr[i]);
    }

    // Upload the file to the root folder of the document library
    this.newFile = scriptList.get_rootFolder().get_files().add(fileCreateInfo);

    clientContext.load(this.newFile);
    clientContext.executeQueryAsync(onSuccess, onFailure);
}

function onSuccess() {
    alert("success")
}

function onFailure() {
    alert(arguments[1].get_message());
}

Can any body please help me out to fix this?