convert userguide in dita-ot package failed

[kodango]

Use this plugin to convert userguide in the dita-ot package, it run successfully but open failed. The error is like: "Unspecified error in comments.xml, Line:0, Column:0".

How to:

$ cd ~/dita-ot-3.0.4
$ sh bin/dita -f docx -i docsrc/userguide.ditamap -o output

After repeated testing, I found this error may be related to the following file. If I comment <xref keyref="2.0-release-notes"/>, the docx file can be opened successfully.

$ grep '<draft-comment' -A2 docsrc/topics/migrating-to-2.0.dita
    plugins by allowing installation from a URL.<draft-comment author="staylor">There are likely other changes that
        should be noted here. See <xref keyref="2.0-release-notes"/>. </draft-comment>
  </shortdesc>