使用Python ftplib上传文件时，"'NoneType‘对象没有’sendall‘属性“

import ftplib

def upload_file(ftp_host, ftp_user, ftp_pass, local_file_path, remote_file_path):
    try:
        # 创建FTP连接对象
        ftp = ftplib.FTP(ftp_host)
        ftp.login(user=ftp_user, passwd=ftp_pass)
        
        # 打开本地文件
        with open(local_file_path, 'rb') as file:
            # 上传文件到FTP服务器
            ftp.storbinary(f'STOR {remote_file_path}', file)
        
        print(f"文件 {local_file_path} 上传成功")
    except ftplib.all_errors as e:
        print(f"FTP错误: {e}")
    finally:
        # 关闭FTP连接
        if 'ftp' in locals():
            ftp.quit()

# 示例调用
upload_file('ftp.example.com', 'username', 'password', 'local_file.txt', 'remote_file.txt')