Exception when importing from on premise YouTrack to Cloud version

I am trying to push my on premise YouTrack to the cloud version. I am using the python client library and using the youtrack2youtrack.py script. On the smaller of my two projects all the issues imported fine including issue attachments.

However on my larger project I am getting and exception when trying to tranfser an attachment on a specific issue and this kills the entire import process.

Transfer attachments

Transfer attachment of BNK-9: AnisotropyArtifacts.jpg

Traceback (most recent call last):

  File "C:\Users\username\Desktop\youtrack-python-api-3.0.2-44\python\youtrack2youtrack.py", line 233, in <module>

    main()

  File "C:\Users\ username \Desktop\youtrack-python-api-3.0.2-44\python\youtrack2youtrack.py", line 21, in main

    youtrack2youtrack(source_url, source_login, source_password, target_url, tar

get_login, target_password, project_ids)

  File "C:\Users\ username\Desktop\youtrack-python-api-3.0.2-44\python\youtrack2youtrack.py", line 217, in youtrack2youtrack    target.createAttachmentFromAttachment(issue.id, a)

  File "C:\Users\ username\Desktop\youtrack-python-api-3.0.2-44\python\youtrack\connection.py", line 105, in createAttachmentFromAttachment

    group=a.group if hasattr(a, 'group') else '')

  File "C:\Users\username\Desktop\youtrack-python-api-3.0.2-44\python\youtrack\connection.py", line 139, in createAttachment

    raise e

urllib2.HTTPError: HTTP Error 404: Not Found

The attachment in question is 209kb on the source server and loads correctly locally. Any ideas? Moreover, is there an eaiser / more robust migration story for moving from on premise youtrack to hosted that I am missing?

I am transferring my entire local youtrack to the cloud and the docs mention that a simple DB copy would do what I want, but presumably I cannot just import a DB file into the cloud version?

Thanks