Notes FP8 (IF1) might stop your custom sidebar plugins from working

We got a call from one of our customers reporting a defect in our midpoints doc.Store sidebar plugin. It worked in Notes 9.0.1FP7 but stopped working after the upgrade to FP8.

I was able to reproduce in our development environment. In the error log, we saw the following error message

at lotus.domino.local.Session.FindOrCreate(Unknown Source)
at lotus.domino.local.Session.FindOrCreate(Unknown Source)
at lotus.domino.local.ViewEntry.getDocument(Unknown Source)
at de.midpoints.docstore.notes.model.DocStoreDocumentCollectionBuilder.calculateDocumentCollection(Unknown Source)
at de.midpoints.docstore.notes.views.DocStoreView$32.run(Unknown Source)
at org.eclipse.core.internal.jobs.Worker.run(Unknown Source)

I was able to find a fix for this particular issue. But there is also an entry in the German Notes Forum reporting similar defects after the upgrade.

I opened a PMR with IBM. IBM is already aware of the issue. According to IBM support, a fix is supposed to be shipped with FP9.

IBM support also proposed a workaround:

The issue does not occur when using the Notes.jar of the 901FP7 with the 901FP8 installation.

Some error messages from the lower levels of the JavaStack:

java.lang.ClassCastException: lotus.domino.local.View
incompatible with lotus.domino.local.Session
at lotus.domino.local.Session.FindOrCreate(Unknown Source)
at lotus.domino.local.Session.FindOrCreate(Unknown Source)
at lotus.domino.local.Database.getView(Unknown Source)
—–

java.lang.ClassCastException: lotus.domino.local.Document
incompatible with lotus.domino.local.Session
at lotus.domino.local.Session.FindOrCreate(Unknown Source)
at lotus.domino.local.Session.FindOrCreate(Unknown Source)
at lotus.domino.local.Database.getDocumentByUNID(Unknown
Source)
—————

java.lang.ClassCastException: lotus.domino.local.Item
incompatible with lotus.domino.local.Session
at lotus.domino.local.Session.FindOrCreate(Unknown Source)
at lotus.domino.local.Session.FindOrCreate(Unknown Source)
at lotus.domino.local.Document.getItems(Unknown Source)

The issue is tracked at IBM under SPR # RGAUALXF5R / APAR LO92228