Error – rest_no_route in custom WP REST API endpoint

I have written a custom REST endpoint for WP REST API to change the user avatar. It is working in my local WordPress installation, but when I try to access the endpoint in my shared host WordPress I get a error saying.

{
    "code": "rest_no_route",
    "message": "No route was found matching the URL and request method",
    "data": {
        "status": 404
    }
}

Even the htaccess files in local installation and the server look identical. The plugin file look like this:

/*Function to get directory URL*/
    function getContentUrl()
    {   
        return WP_CONTENT_URL."/uploads/avatars/";
    }

    /*Function to get directory local path*/
    function getContentDirectory(){
        return WP_CONTENT_DIR."/uploads/avatars/";
    }

    /*Initializing Rest API Endpoint*/
    add_action('rest_api_init',function(){
        /*--Avatar Change Custom API--*/
        register_rest_route('custom/v1', '/avatarchange/',array(
            'methods' => 'POST',
            'callback' => 'changeAvatar',
            'args' => array(
                'userid' => array(),
                'fname' => array(),
                'lname' => array(),
                'image' => array(),
            ),
            'permission_callback' => function(){
                //return current_user_can( 'read' );
            return true;
            } 
        ));
        /*--Get Userid from Email Custom API--*/
        register_rest_route('custom/v1', '/getuid/',array(
            'methods' => 'POST',
            'callback' => 'getUidFromEmail',
            'args' => array(
                'email' => array(),
            ),
            'permission_callback' => function(){
                return current_user_can( 'read' );
            } 
        ));
    });