IE9 hangs local Flask instance

Question

A web app I am working on works fine under Firefox and IE8 from virtual box. But when I try to load it with IE9, it tries to load the page but after a while stops loading. Then I try to load the same url with Firefox again and it doesn't load at all. Then I restart Flask and the same happens - I can work normally with the app through FF but not IE9. Looks like a kind of a bug, doesn't it?

Here is the exception Python throws:

Exception happened during processing of request from ('127.0.0.1', 6924)
Traceback (most recent call last):
  File "C:\Python27\lib\SocketServer.py", line 284, in _handle_request_noblock
    self.process_request(request, client_address)
  File "C:\Python27\lib\SocketServer.py", line 310, in process_request
    self.finish_request(request, client_address)
  File "C:\Python27\lib\SocketServer.py", line 323, in finish_request
    self.RequestHandlerClass(request, client_address, self)
  File "C:\Python27\lib\SocketServer.py", line 639, in __init__
    self.handle()
  File "C:\Users\Cosmo\AppData\Roaming\Python\Python27\site-packages\werkzeug\serving.py", line 189, in handle
    return rv
UnboundLocalError: local variable 'rv' referenced before assignment

I have uploaded code to my hosting and it works fine there.

I think the issue from this thread is similar to my one.

Could you please share your code? Otherwise, we have no way of reproducing the problem. Also, which version of python are you using? — linqq, Nov 19 '11 at 20:30

score 3 · Accepted Answer · answered Nov 19 '11 at 20:37

3

Try using a git version of werkzeug. According to the author, a similar bug was recently fixed.

answered Nov 19 '11 at 20:37

linqq

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@trinth try to use app.run(threaded=True) instead of app.run() that is single-threaded by default, it worked for me :) – Juande Carrion Sep 19 '13 at 14:57

score 2 · Answer 2 · edited May 23 '17 at 11:51

2

I've been having problems with IE hanging my flask server with more recent versions of Flask/Werkzeug (+2 years from this thread). The solution I found was to use run(threaded=True) as described in this other question: Can I serve multiple clients using just Flask app.run() as standalone?

edited May 23 '17 at 11:51

Community

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answered Nov 28 '13 at 06:49

Vroo

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I fixed the typo. Did you really think that was a constructive comment? There's a reason that stackoverflow lets you suggest edits to other people's answers. – Vroo Dec 09 '13 at 20:09
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Agree. I would have welcomed a correction. Saying that there's no true in Python is snarky. – Vroo Dec 21 '13 at 06:29
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This answer should be on top. A long time has gone since the question was originally posted, and I bet that most if not all of the people reaching to it now are looking for this answer, not for the development version of werkzeug – rll Aug 04 '15 at 15:40

IE9 hangs local Flask instance

2 Answers2