使用Paramiko连接SFTP出现BufferError问题求助

我使用以下Python代码通过Paramiko连接SFTP服务器拉取文件，这是一段基础的SFTP连接代码：

def get_fund_files():
    host, port = "ftp.example.com", 22
    transport = paramiko.Transport((host, port))
    # Auth
    username, password = "user", "password"
    transport.connect(None, username, password)
    # Go!
    with paramiko.SFTPClient.from_transport(transport) as sftp:

目前这段代码在我的Bitnami Ubuntu服务器上突然无法运行，出现如下错误：

Traceback (most recent call last):
  File "main.py", line 288, in <module>
    main()
  File "main.py", line 15, in main
    get_fund_files()
  File "main.py", line 28, in get_fund_files
    transport.connect(None, username, password)
  File "/usr/lib/python3/dist-packages/paramiko/transport.py", line 1263, in connect
    self.auth_password(username, password)
  File "/usr/lib/python3/dist-packages/paramiko/transport.py", line 1431, in auth_password
    self.auth_handler.auth_password(username, password, my_event)
  File "/usr/lib/python3/dist-packages/paramiko/auth_handler.py", line 138, in auth_password
    self._request_auth()
  File "/usr/lib/python3/dist-packages/paramiko/auth_handler.py", line 189, in _request_auth
    self.transport._send_message(m)
  File "/usr/lib/python3/dist-packages/paramiko/transport.py", line 1766, in _send_message
    self.packetizer.send_message(data)
  File "/usr/lib/python3/dist-packages/paramiko/packet.py", line 399, in send_message
    out = self.__block_engine_out.update(packet)
  File "/usr/lib/python3/dist-packages/cryptography/hazmat/primitives/ciphers/base.py", line 149, in update
    return self._ctx.update(data)
  File "/usr/lib/python3/dist-packages/cryptography/hazmat/backends/openssl/ciphers.py", line 124, in update
    n = self.update_into(data, buf)
  File "/usr/lib/python3/dist-packages/cryptography/hazmat/backends/openssl/ciphers.py", line 140, in update_into
    self._backend._ffi.from_buffer(data, require_writable=True), len(data)
BufferError: Object is not writable.

相同代码在克隆实例上运行正常，且服务器和SFTP无已知变更，错误发生在transport.connect(None, username, password)步骤。

• 对齐依赖库版本：对比克隆实例和故障服务器的paramiko、cryptography版本，运行pip list | grep -E "paramiko|cryptography"查看版本号，将故障服务器的库版本同步到克隆实例的版本，比如执行pip install cryptography==x.x.x paramiko==x.x.x（替换为实际匹配的版本号）。
• 修复或重装依赖：若存在库文件损坏，先卸载现有库：pip uninstall -y paramiko cryptography，再重新安装；如果是系统级Python依赖，用apt reinstall python3-paramiko python3-cryptography修复系统包。
• 检查OpenSSL兼容性：运行openssl version对比两个实例的OpenSSL版本，若差异较大，尝试升级或降级到兼容版本（操作前注意系统稳定性）。
• 添加调试日志：在代码开头加入日志配置，获取加密协商阶段的详细信息：

  import logging
  logging.basicConfig(level=logging.DEBUG)
  

• 指定加密算法：手动设置兼容的加密算法集合，避免协商到有问题的算法：

  transport = paramiko.Transport((host, port))
  transport.set_security_options(ciphers=['aes256-ctr', 'aes192-ctr', 'aes128-ctr'])
  

内容的提问来源于stack exchange，提问作者Imerial