When migrating mailbox data migappworker hangs a few times during each migration run.
This kind of event is in the eventlog:
Reporting queued error: faulting application migappworker.exe, version 22.214.171.124, faulting module nnotes.dll, version 126.96.36.19969, fault address 0x00001457.
This can be cause by an issue with the Notes Client
Check for an error in the crashdump-files in the C:\Program Files\lotus\notes\data\IBM_TECHNICAL_SUPPORT path.
The error is:
PANIC: Invalid pool free chain
This ibm-article describes the problem and a solution.
Upgrading to Notes client 7.0.3 and rerunning the batch migration should fix the issue.