It seems impossible to clone an Element created without a document:

  >>> Element('foo').cloneNode(False)
  Traceback (most recent call last):
    File "<stdin>", line 1, in <module>
    File "/usr/lib/python2.5/xml/dom/minidom.py", line 211, in cloneNode
      return _clone_node(self, deep, self.ownerDocument or self)
    File "/usr/lib/python2.5/xml/dom/minidom.py", line 1814, in _clone_node
      if node.ownerDocument.isSameNode(newOwnerDocument):
  AttributeError: 'NoneType' object has no attribute 'isSameNode'

The documentation claims that cloneNode was fixed for releases
"subsequent" to 2.0, but this doesn't appear to be true.

http://docs.python.org/library/xml.dom.minidom.html#xml.dom.minidom.Node.cloneNode

A similar issue occurs when attempting to import a node into a document
(something I tried as a work-around for this failure):

  >>> d.importNode(e, False)
  Traceback (most recent call last):
    File "<stdin>", line 1, in <module>
    File "/usr/lib/python2.5/xml/dom/minidom.py", line 1737, in importNode
      return _clone_node(node, deep, self)
    File "/usr/lib/python2.5/xml/dom/minidom.py", line 1814, in _clone_node
      if node.ownerDocument.isSameNode(newOwnerDocument):
  AttributeError: 'NoneType' object has no attribute 'isSameNode'

Has this simply slipped under the radar?

This patch allows the cloning of elements that do not have a document owner.

If a node does not have a document owner, a new document owner is created for the clone.

This looks like a duplicate of https://bugs.python.org/issue15290 .

15290 was closed as invalid, and the submitter was told that the
code should be changed to not rely on creating elements outside
of the document interface.

I encountered the same problem when trying to port Twisted to Python 3.

Thanks for your detective work, Craig. MvL is correct that those classes should be created via a Document object. I'm marking issue 15290 as a duplicate of this.

Note that we can reopen this if you'd like to propose a documentation patch or PR to make the current docs clearer. Thanks!