[Zope] Undo error

[Dieter Maurer]

Bo M. Maryniuck writes:
 > I always have a trouble to undo something.
 > Zope: 2.5, not updated
 > OS: Linux SuSE 8.0 Pro
 > Session is on ZODB, not in temp folder.
 > 
 > Anybody know what this error means and how to avoid this?
 > 
 > Error Type: UndoError
 > Error Value: Couldn't undo change to '\x00\x00\x00\x00\x00\x00\x1c4' because non-undoable transaction
I see two potential reasons:

  1. The transaction references a set of objects.
     At least one of these objects has later been changed by another
     transaction. The former transaction cannot be undone without 
     the latter one (because this would give you some inconsistency)

  2. A single Zope-transaction can consist of an undoable transaction
     (e.g. against a ZODB on top of an undoable storage)
     and a non-undoable transaction (e.g. against a relational database).
     Then the whole transaction is non-undoable (because you cannot
     undo the effect in the relational database).

     Up to now, I did not know that Zope supports this kind
     of undoable transaction. But it would be fine when it does.


Dieter