There is initial content - many nodes under one root node. This content gets moved from one root node into another root by concurrent threads - one thread opens one session, takes one child and perform one move operation. It appears that this setup can cause InvalidItemStateException.

Caused by: javax.jcr.InvalidItemStateException: This session tried to save changes to node with key 'Cannot locate child node: 4c24b267505d649a2c9bcd-b65b-494b-a15d-e791d40f6ac4 within parent: 4c24b267505d64df01b090-ef0d-4e4e-b80a-b52a832c988a', but it was removed by another session.

See full log in attachment.

Please note that this exception is floating and looks like depends on hardware load.