Failure when converting editor format to storage format.

The Confluence 4.2 rich text editor just reported the following error:

Failure when converting editor format to storage format.

I have not been able to reproduce this error, but here is (only roughly, sorry) what I did to create it:

1. Create a new page.
2. Enter two paragraphs of text, with no other formatting than a link to a user name entered via autocompletion (typing [, then ~, then the user name); on the first attempt, the autocompletion created a link to the profile image, rather than to the user name. (I think the secret must be in here somewhere; the deletion of the first attempt, and the re-creation of the link to the user name. I know that I must have been doing something wrong the first time around for the link to the profile image to have been created, but I am afraid I cannot recall the exact keystrokes.)

After receiving the error (and hence, being unable to save the page), I deleted what I thought might be the problem (the link), and then opened the Source Editor plugin to view the XML. The second paragraph, that had contained the link, had the following class attribute:

<p class="confluence-link">

I deleted the class attribute, returned to the rich text editor, re-created the link to the user name, and saved the page without further ado.

In my attempts to reproduce this error, I managed to create XML with the following (to me, extraneous - and, certainly, as far as the view presented by the rich text editor is concerned, invisible) span element around the ac:link:

<p>jhdfkjhdfkdfj <span class="confluence-link">
    <ac:link>
      <ri:user ri:username="grahan01"/>
      <ac:plain-text-link-body><![CDATA[~grahan01]]></ac:plain-text-link-body>
    </ac:link>
  </span> dkjdfkjdfkjdf.</p>