public function storeUser($user_login, $user_password, $user_name, $user_middle_name, $user_last_name, $user_group) {
        $uuid = uniqid('', true);
        $hash = $this->hashSSHA($user_password);
        $user_encrypted_pass = $hash["user_encrypted_pass"]; // encrypted password
        $user_salt = $hash["user_salt"]; // salt

        $stmt = $this->conn->prepare("INSERT INTO users_table(user_uniqueid, user_login, user_encrypted_pass, user_salt, user_name, user_middle_name, user_last_name, user_group, user_created) VALUES(?, ?, ?, ?, ?, ?, ?, ?, NOW())");
 Ошибка здесь-> $stmt->bind_param("ssssssss", $uuid, $user_login, $user_encrypted_pass, $user_salt, $user_name, $user_middle_name, $user_last_name, $user_group);
        $result = $stmt->execute();
        $stmt->close();

        // check for successful store
        if ($result) {
            $stmt = $this->conn->prepare("SELECT * FROM users_table WHERE user_login = ?");
            $stmt->bind_param("s", $user_login);
            $stmt->execute();
            $user = $stmt->get_result()->fetch_assoc();
            $stmt->close();

            return $user_login;
        } else {
            return false;
        }
    }