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Editorial Team
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Asked: 2026-06-03T03:13:57+00:00

In a web-application (using Flask), I get the following error: Unable to retrieve the

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In a web-application (using Flask), I get the following error:

Unable to retrieve the thumbnail for u'/var/data/uploads/2012/03/22/12 Gerd\xb4s Banjo Trio 1024.jpg'
Traceback (most recent call last):
 File "/var/www/beta/env/lib/python2.7/site-packages/dblib-1.0dev3-py2.7.egg/dblib/orm/file.py", line 169, in get_thumbnail
   if not exists(filename):
 File "/usr/lib/python2.7/genericpath.py", line 18, in exists
   os.stat(path)
UnicodeEncodeError: 'ascii' codec can't encode character u'\xb4' in position 52: ordinal not in range(128)

Note that I include the repr() of the file name in the logged error. This shows that the file name is passed as a Unicode instance. So much is correct…

If I run the culprit using the python interpreter, it works as expected:

>>> from os.path import exists
>>> exists(u'/var/data/uploads/2012/03/22/12 Gerd\xb4s Banjo Trio 1024.jpg')
True

So obviously, while running in the Flask environment, Python thinks it should encode the file-name using the ASCII codec instead of UTF-8. I deployed the application using mod_wsgi behind the Apache httpd.

I assume I have to tell either one of them to use UTF-8 somewhere? But where?

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1 Answer

  1. Editorial Team

    See Django docs for same issue. When using mod_wsgi, should be same solution:

    https://docs.djangoproject.com/en/dev/howto/deployment/wsgi/modwsgi/#if-you-get-a-unicodeencodeerror

    Excerpt from the above linked doc:

    […] you must ensure that the environment used to start Apache is
    configured to accept non-ASCII file names. If your environment is not
    correctly configured, you will trigger UnicodeEncodeError exceptions
    when calling functions like the ones in os.path on filenames that
    contain non-ASCII characters.

    To avoid these problems, the environment used to start Apache should
    contain settings analogous to the following:

    export LANG='en_US.UTF-8'
export LC_ALL='en_US.UTF-8'

    Consult the documentation for your operating system for the
    appropriate syntax and location to put these configuration items;
    /etc/apache2/envvars is a common location on Unix platforms. Once
    you have added these statements to your environment, restart Apache.

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