[Zope] Broken product after relocating ZODB (was: [Zope] problem moving ZODB to new ... )

[Darran Edmundson]

Just before the Christmas break, I was trying to
unravel the following mystery:

>DE> We have just migrated from a machine running
>DE> Zope with the ZServer to a different machine
>DE> running Zope with an Apache web server.  But 
>DE> we have a problem, namely, after copying over 
>DE> the Data.fs ZODB to the new site, Zope cannot
>DE> find a needed (but installed) product (Navigator).
>
>DE> This product definitely exists:
>DE> /Zope-2.1.0-src/lib/python/Products/Navigator
>DE> so why is Zope not seeing it?
>DE> i
>DE> From the manager view of the ZODB:
>
>DE> Product at /optics / Control_Panel / Products / Navigator  
>DE> There are currently no items in Installed product Navigator (Navigator
>DE> Product, Version 1.02)  


Martijn Pieters replied:

>That sounds like a working Product to me. Did it have items there
>before the move? What is actually not working, do you get tracebacks?
[snip]

Yes, instances of Jonas' Navigator product show up with a pretty
little bullseye gif image in the management view.  I had a number
of NavItems scattered throughout my ZODB with which all site 
navigation was handled.  Now, these all show up as "link to a broken
product".  Further, the Navigator product no longer shows up in
the drop-down "Add" selection box of the management interface.
However, the pure-python Navigator product does show up in the management 
interface:

DE> Product at /optics / Control_Panel / Products / Navigator  
DE> There are currently no items in Installed product Navigator (Navigator
DE> Product, Version 1.02)  


so Zope has seen it in the /Zope-2.1.0-src/lib/python/Products/Navigator
directory.  (I take it from Martijn's last message that the "currently 
no items" blurb is standard for pure-python products.)  I just 
re-verified that Navigator does work properly when added to a Zope 
running ZServer.  The question: is my inability to use Navigator 
caused by simply copying over Data.fs from the old site, or does it
indicate a problem with our Zope under Apache setup?  There are no 
errors or tracebacks other than those generated from this pseudo-
missing product.