[Zope] Trouble migrating from Zope 2.5.x to Zope 2.9.x

[Doug Morse]

Hello Fellow Zopers,

I'm trying to migrate an older Zope installation (2.5.x) to Zope 2.9 and I'm
having some trouble.  I can mount the old ZODB in the new installation -- it
shows up under the database control panel with the correct size (4.4M) --
but it appears to be empty.  By "empty", I mean there are no folders or
objects present when I view the mount point using the ZMI, and I get
"Resource Not Found" errors when trying to view object I know to be there.
I'm not getting any error messages within the ZMI or in the events.log file
regarding problems with the older Data.fs file or mounting it.

I'm wondering if there's some sort of "upgrading" of the ZODB file I need to
perform?  Any help with this would be MOST appreciated, as I'm not turning
up anything in the docs, with google, or any other means I can think of, and
I need to get this site migrated.

Just for completeness: The only thing different about the new Zope
installation is that the old Data.fs file is being mounted within Zope under
a subdirectory (e.g., "/sitename") instead of the root directory (i.e.,
"/"). There's a new ZODB mounted at the root directory, and several other
new ZODBs mounted in other subdirectories for new sites -- they all
work fine but also were created using Zope 2.9, not Zope 2.5.

Thanks!
Doug