To troubleshoot or diagnose any issues with bulk import, you can enable logging.
To enable debugging for the Bulk Import tool, use the following command:
log4j.logger.org.alfresco.repo.bulkimport=DEBUG
Set the debug statements to at least INFO level:
log4j.logger.org.alfresco.repo.batch.BatchProcessor=info
You can also enable logging for the transaction handler to identify any transactional issues during the import:
log4j.logger.org.alfresco.repo.transaction.RetryingTransactionHelper=info