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Python 3中解决WSGI自定义函数与make_server报错的方法

云舒
云舒
发布时间：2026-10-13 | 4人浏览过
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本文解决Python 3中运行WSGI服务器时遇到的报错问题。当自定义wsgi函数返回字符串而非bytes时，会触发TypeError。通过定位handlers.py源码中的finish_response方法，发现write方法要求参数为bytes类型。解决方案是在返回数据前调用encode()进行编码，从而消除报错并恢复服务正常运行。

#coding:utf-8

from wsgiref.simple_server import make_server

def RunServer(environ, start_response):
  start_response('200 OK', [('Content-Type', 'text/html')])
  return '<h1>Hello, web!</h1>'

if __name__ == '__main__':
  httpd = make_server('localhost', 8000, RunServer)
  print ("Serving HTTP on port 8000...")
  httpd.serve_forever()

这段代码在Python 2.7环境下可以正常运行，但迁移到Python 3.4后执行时却出现报错，具体报错信息如下：

Serving HTTP on port 8000...
127.0.0.1 - - [12/Apr/2016 16:44:17] "GET / HTTP/1.1" 200 0
Traceback (most recent call last):
File "C:\Python34\lib\wsgiref\handlers.py", line 138, in run
self.finish_response()
File "C:\Python34\lib\wsgiref\handlers.py", line 181, in finish_response
self.write(data)
File "C:\Python34\lib\wsgiref\handlers.py", line 267, in write
"write() argument must be a bytes instance"
AssertionError: write() argument must be a bytes instance
127.0.0.1 - - [12/Apr/2016 16:44:17] "GET / HTTP/1.1" 500 59
Traceback (most recent call last):
File "C:\Python34\lib\wsgiref\handlers.py", line 138, in run
self.finish_response()
File "C:\Python34\lib\wsgiref\handlers.py", line 181, in finish_response
self.write(data)
File "C:\Python34\lib\wsgiref\handlers.py", line 267, in write
"write() argument must be a bytes instance"
AssertionError: write() argument must be a bytes instance

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "C:\Python34\lib\wsgiref\handlers.py", line 141, in run
self.handle_error()
File "C:\Python34\lib\wsgiref\handlers.py", line 369, in handle_error
self.finish_response()
File "C:\Python34\lib\wsgiref\handlers.py", line 181, in finish_response
self.write(data)
File "C:\Python34\lib\wsgiref\handlers.py", line 275, in write
self.send_headers()
File "C:\Python34\lib\wsgiref\handlers.py", line 332, in send_headers
if not self.origin_server or self.client_is_modern():
File "C:\Python34\lib\wsgiref\handlers.py", line 345, in client_is_modern
return self.environ['SERVER_PROTOCOL'].upper() != 'HTTP/0.9'
TypeError: 'NoneType' object is not subscriptable

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
----------------------------------------
Exception happened during processing of request from ('127.0.0.1', 60566)
File "C:\Python34\lib\socketserver.py", line 305, in _handle_request_noblock
self.process_request(request, client_address)
File "C:\Python34\lib\socketserver.py", line 331, in process_request
self.finish_request(request, client_address)
File "C:\Python34\lib\socketserver.py", line 344, in finish_request
self.RequestHandlerClass(request, client_address, self)
File "C:\Python34\lib\socketserver.py", line 673, in __init__
self.handle()
File "C:\Python34\lib\wsgiref\simple_server.py", line 133, in handle
handler.run(self.server.get_app())
File "C:\Python34\lib\wsgiref\handlers.py", line 144, in run
self.close()
File "C:\Python34\lib\wsgiref\simple_server.py", line 35, in close
self.status.split(' ',1)[0], self.bytes_sent
AttributeError: 'NoneType' object has no attribute 'split'
----------------------------------------
----------------------------------------
Exception happened during processing of request from ('127.0.0.1', 60568)
----------------------------------------
127.0.0.1 - - [12/Apr/2016 16:44:18] "GET / HTTP/1.1" 200 0
Traceback (most recent call last):
File "C:\Python34\lib\wsgiref\handlers.py", line 138, in run
self.finish_response()
File "C:\Python34\lib\wsgiref\handlers.py", line 181, in finish_response
self.write(data)
File "C:\Python34\lib\wsgiref\handlers.py", line 267, in write
"write() argument must be a bytes instance"
AssertionError: write() argument must be a bytes instance
127.0.0.1 - - [12/Apr/2016 16:44:18] "GET / HTTP/1.1" 500 59
Traceback (most recent call last):
File "C:\Python34\lib\wsgiref\handlers.py", line 138, in run
self.finish_response()
File "C:\Python34\lib\wsgiref\handlers.py", line 181, in finish_response
self.write(data)
File "C:\Python34\lib\wsgiref\handlers.py", line 267, in write
"write() argument must be a bytes instance"
AssertionError: write() argument must be a bytes instance

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "C:\Python34\lib\wsgiref\handlers.py", line 141, in run
self.handle_error()
File "C:\Python34\lib\wsgiref\handlers.py", line 369, in handle_error
self.finish_response()
File "C:\Python34\lib\wsgiref\handlers.py", line 181, in finish_response
self.write(data)
File "C:\Python34\lib\wsgiref\handlers.py", line 275, in write
self.send_headers()
File "C:\Python34\lib\wsgiref\handlers.py", line 332, in send_headers
if not self.origin_server or self.client_is_modern():
File "C:\Python34\lib\wsgiref\handlers.py", line 345, in client_is_modern
return self.environ['SERVER_PROTOCOL'].upper() != 'HTTP/0.9'
TypeError: 'NoneType' object is not subscriptable

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "C:\Python34\lib\socketserver.py", line 305, in _handle_request_noblock
self.process_request(request, client_address)
File "C:\Python34\lib\socketserver.py", line 331, in process_request
self.finish_request(request, client_address)
File "C:\Python34\lib\socketserver.py", line 344, in finish_request
self.RequestHandlerClass(request, client_address, self)
File "C:\Python34\lib\socketserver.py", line 673, in __init__
self.handle()
File "C:\Python34\lib\wsgiref\simple_server.py", line 133, in handle
handler.run(self.server.get_app())
File "C:\Python34\lib\wsgiref\handlers.py", line 144, in run
self.close()
File "C:\Python34\lib\wsgiref\simple_server.py", line 35, in close
self.status.split(' ',1)[0], self.bytes_sent
AttributeError: 'NoneType' object has no attribute 'split'

乍看之下，错误信息繁多，容易让人不知所措。经过多次使用Google和百度搜索，虽然Google能检索到一些相关信息，

但由于英文阅读能力有限，难以完全理解其含义；而百度搜索到的结果多为无效内容，毫无帮助。最终只能硬着头皮，逐步查阅相关源码。

首先，根据报错第一行的提示：

File "C:\Python34\lib\wsgiref\handlers.py", line 138, in run
self.finish_response()

我使用的编辑器是PyCharm，通过定位到handlers.py文件的第138行，并按住Ctrl键点击文件中的finish_response()方法，

即可找到self.finish_response()的定义位置。根据第二条报错提示：

File "C:\Python34\lib\wsgiref\handlers.py", line 181, in finish_response
self.write(data)

发现错误出在write方法上。再次按住Ctrl键点击write方法以查看其定义，发现第一行代码就定义了一条断言报错：

assert type(data) is bytes, \
"write() argument must be a bytes instance"

对照上述报错信息，推测可能是变量data的类型并非bytes。因此，在handlers.py第181行的代码self.write(data)上方添加一句：

data=data.encode()，再次刷新程序后，发现所有报错均消失，程序得以正常运行。

以上关于解决Python 3中自定义WSGI函数及make_server函数报错的内容分享到此结束，希望能为各位提供有益参考，也欢迎大家继续支持本站。

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相关标签: Python WSGI 错误排查 Python 3

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