ImportError: pyexpat.so: symbol XML_SetHashSalt, version EXPAT_2_0_1_RH not defined in file libexpat.so.1

[anonymous]

I've recently tried to install Trac 1.0 on CentOS 6.3 I tried various method of installing… first via an RPM I found, then I removed that and installed via easy_install. Both methods produced the same bug. Below is the full output from the apache error log - this is generated when I try to browse to the trac project online.

[Thu Jan 31 22:55:29 2013] [error] [client 41.185.115.143] mod_python (pid=25682, interpreter='main_interpreter', phase='PythonHandler', handler='trac.web.modpython_frontend'): Application error
[Thu Jan 31 22:55:29 2013] [error] [client 41.185.115.143] ServerName: 'mydomain.net'
[Thu Jan 31 22:55:29 2013] [error] [client 41.185.115.143] DocumentRoot: '/var/www/vhosts/mydomain.net/httpdocs'
[Thu Jan 31 22:55:29 2013] [error] [client 41.185.115.143] URI: '/trac'
[Thu Jan 31 22:55:29 2013] [error] [client 41.185.115.143] Location: '/trac'
[Thu Jan 31 22:55:29 2013] [error] [client 41.185.115.143] Directory: None
[Thu Jan 31 22:55:29 2013] [error] [client 41.185.115.143] Filename: '/var/www/vhosts/mydomain.net/httpdocs/trac'
[Thu Jan 31 22:55:29 2013] [error] [client 41.185.115.143] PathInfo: ''
[Thu Jan 31 22:55:29 2013] [error] [client 41.185.115.143] Traceback (most recent call last):
[Thu Jan 31 22:55:29 2013] [error] [client 41.185.115.143]   File "/usr/lib64/python2.6/site-packages/mod_python/importer.py", line 1537, in HandlerDispatch\n    default=default_handler, arg=req, silent=hlist.silent)
[Thu Jan 31 22:55:29 2013] [error] [client 41.185.115.143]   File "/usr/lib64/python2.6/site-packages/mod_python/importer.py", line 1202, in _process_target\n    module = import_module(module_name, path=path)
[Thu Jan 31 22:55:29 2013] [error] [client 41.185.115.143]   File "/usr/lib64/python2.6/site-packages/mod_python/importer.py", line 304, in import_module\n    return __import__(module_name, {}, {}, ['*'])
[Thu Jan 31 22:55:29 2013] [error] [client 41.185.115.143]   File "/usr/lib/python2.6/site-packages/Trac-1.0-py2.6.egg/trac/web/__init__.py", line 23, in <module>\n    from trac.web.api import *
[Thu Jan 31 22:55:29 2013] [error] [client 41.185.115.143]   File "/usr/lib/python2.6/site-packages/Trac-1.0-py2.6.egg/trac/web/api.py", line 32, in <module>\n    from trac.util import get_last_traceback, unquote
[Thu Jan 31 22:55:29 2013] [error] [client 41.185.115.143]   File "/usr/lib/python2.6/site-packages/Trac-1.0-py2.6.egg/trac/util/__init__.py", line 37, in <module>\n    from .text import exception_to_unicode, to_unicode
[Thu Jan 31 22:55:29 2013] [error] [client 41.185.115.143]   File "/usr/lib/python2.6/site-packages/Trac-1.0-py2.6.egg/trac/util/text.py", line 30, in <module>\n    from trac.util.translation import _
[Thu Jan 31 22:55:29 2013] [error] [client 41.185.115.143]   File "/usr/lib/python2.6/site-packages/Trac-1.0-py2.6.egg/trac/util/translation.py", line 21, in <module>\n    from genshi.builder import tag
[Thu Jan 31 22:55:29 2013] [error] [client 41.185.115.143]   File "/usr/lib/python2.6/site-packages/Genshi-0.6-py2.6.egg/genshi/__init__.py", line 26, in <module>\n    from genshi.input import ParseError, XML, HTML
[Thu Jan 31 22:55:29 2013] [error] [client 41.185.115.143]   File "/usr/lib/python2.6/site-packages/Genshi-0.6-py2.6.egg/genshi/input.py", line 22, in <module>\n    from xml.parsers import expat
[Thu Jan 31 22:55:29 2013] [error] [client 41.185.115.143]   File "/usr/lib64/python2.6/xml/parsers/expat.py", line 4, in <module>\n    from pyexpat import *
[Thu Jan 31 22:55:29 2013] [error] [client 41.185.115.143] ImportError: /usr/lib64/python2.6/lib-dynload/pyexpat.so: symbol XML_SetHashSalt, version EXPAT_2_0_1_RH not defined in file libexpat.so.1 with link time reference
[Thu Jan 31 22:55:30 2013] [error] [client 41.185.115.143] File does not exist: /var/www/vhosts/mydomain.net/httpdocs/trunk/favicon.ico

This is my trac.conf:

# /etc/httpd/conf.d/trac.conf
#
# trac
<Location /trac>
  SetHandler mod_python
  PythonInterpreter main_interpreter
  PythonHandler trac.web.modpython_frontend
  PythonOption TracEnvParentDir /var/trac
  PythonOption TracUriRoot /trac
</Location>

[Remy Blank]

Please use the MailingList and IrcChannel for InstallationIssues. Thank you.

[trac@…]

I tried all of those and got nowhere. This issue persists for me and not just with mod_python, also with mod_wsgi. I understand that this is some sort of distro issue but I've met all the pre-requisites… python 2.6.6 and followed the Trac installation instructions to the letter. I'm a little desperate to try and find a way to get this working. I've drawn blanks on google, IRC and the MailingList. Any suggestion would be most welcome.