I get this error when enabling the rst plugin. I am running IkiWiki 3.20130904.1ubuntu1 on Ubuntu 14.04 in a non-English UTF-8 locale; the pages can also contain characters in UTF-8 encoding.

uncaught exception: 'ascii' codec can't encode character u'\xa9' in position 13: ordinal not in range(128)
Traceback (most recent call last):
  File "/usr/lib/ikiwiki/plugins/proxy.py", line 309, in run
    self._in_fd, self._out_fd)
  File "/usr/lib/ikiwiki/plugins/proxy.py", line 192, in handle_rpc
    ret = self._dispatcher.dispatch(method, params)
  File "/usr/lib/ikiwiki/plugins/proxy.py", line 84, in dispatch
    return self._dispatch(method, params)
  File "/usr/lib/python2.7/SimpleXMLRPCServer.py", line 420, in _dispatch
    return func(*params)
  File "/usr/lib/ikiwiki/plugins/proxy.py", line 253, in hook_proxy
    "{0} hook `{1}' returned: [{2}]".format(type, name, ret))
UnicodeEncodeError: 'ascii' codec can't encode character u'\xa9' in position 13: ordinal not in range(128)

Traceback (most recent call last):
  File "/usr/lib/ikiwiki/plugins/rst", line 86, in <module>
    proxy.run()
  File "/usr/lib/ikiwiki/plugins/proxy.py", line 317, in run
    self.error('uncaught exception: {0}\n{1}'.format(e, tb))
  File "/usr/lib/ikiwiki/plugins/proxy.py", line 298, in error
    self.rpc('error', msg)
  File "/usr/lib/ikiwiki/plugins/proxy.py", line 233, in rpc
    *args, **kwargs)
  File "/usr/lib/ikiwiki/plugins/proxy.py", line 173, in send_rpc
    raise GoingDown()
proxy.py.GoingDown

A fix is akin to the one for http://ikiwiki.info/bugs/proxy.py_utf8_troubles/: change ...format(type, name, ret) in proxy.py line 253 to format(type, name, repr(ret)) (which should not hurt since it's a message for debugging purposes only).

this is fixed in commit 154c4ea9 (november 2013), which is included in 3.20140227. --chrysn