[Zope] Problem with upgrade from Zope 2.6.1 to Zope 2.9.4

[yogeen honnavar]

Dear users,
            we migrated a zope application from Zope
2.6.1 to Zope 2.9.4 by copying the Data.fs file to the
new installation. given below is the trace. can anyone
suggest what is the problem and corrective measures.
   we r not able to understand whether the error
occurs at mytestflow or at index object. pls clarify.
    thanks and regards
    -yogeen

2006-09-12T16:38:47 ERROR Zope.SiteErrorLog
http://mywebsite.com:8080/xxx/yyy/ll/ll_start
Traceback (innermost last):
  Module ZPublisher.Publish, line 115, in publish
  Module ZPublisher.mapply, line 88, in mapply
  Module ZPublisher.Publish, line 41, in call_object
  Module OFS.DTMLMethod, line 144, in __call__
   - <DTMLMethod at /xxx/yyy/ll/ll_start>
   - URL:
http://mywebsite.com:8080/xxx/yyy/ll/ll_start/manage_main
   - Physical Path: /xxx/yyy/ll/ll_start
  Module DocumentTemplate.DT_String, line 476, in
__call__
  Module DocumentTemplate.DT_Let, line 76, in render
  Module DocumentTemplate.DT_Let, line 76, in render
  Module DocumentTemplate.DT_Let, line 75, in render
  Module DocumentTemplate.DT_Util, line 196, in eval
  - __traceback_info__: mytestflow
  Module <string>, line 1, in <expression>
  Module Products.OpenFlow.openflow, line 379, in
addInstance
  Module Products.OpenFlow.process, line 144, in
addInstance
  Module Products.OpenFlow.instance, line 41, in
addInstance
  Module Products.OpenFlow.instance, line 68, in
manage_addInstance
  Module Products.OpenFlow.instance, line 57, in
safeSetObject
  Module Products.BTreeFolder2.BTreeFolder2, line 446,
in _setObject
  Module zope.event, line 23, in notify
  Module zope.app.event.dispatching, line 66, in
dispatch
  Module zope.component, line 181, in subscribers
  Module zope.component.site, line 89, in subscribers
  Module zope.interface.adapter, line 481, in
subscribers
  Module zope.app.event.objectevent, line 192, in
objectEventNotify
  Module zope.component, line 181, in subscribers
  Module zope.component.site, line 89, in subscribers
  Module zope.interface.adapter, line 481, in
subscribers
  Module OFS.subscribers, line 114, in
dispatchObjectMovedEvent
  Module OFS.subscribers, line 137, in
callManageAfterAdd
  Module Products.ZCatalog.CatalogPathAwareness, line
42, in manage_afterAdd
  Module Products.ZCatalog.CatalogPathAwareness, line
99, in index_object
  Module Products.ZCatalog.ZCatalog, line 567, in
catalog_object
  Module Products.ZCatalog.Catalog, line 360, in
catalogObject
  Module Products.PluginIndexes.PathIndex.PathIndex,
line 124, in index_object
AttributeError: _length



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