we are getting problems converting some html files into pdfs. We can build using 6.0 rev 6 and rev 7, but not rev 8.

The error msg is:

prince: internal error: pack_blocks: empty list.

I can email in a sample html file on request.

Please email me (mikeday@yeslogic.com) a sample document demonstrating the bug, I'm hoping that this is an issue we have just recently fixed.

sample emailed to you

This issue is fixed in the beta version of Prince 7.0, available now.

What was the issue? We have the same issue, but are unable to upgrade, is there some specific html that causes this?

There have been various issues with inline blocks and floats that have caused this error, which should be fixed for good now. It may be possible to workaround it by carefully modifying your documents, but upgrading would be the simplest solution, and may bring other benefits as well.