I came across an issue today running the P12 migration tool and thought I would share the error and simple fix. The command prompt didn’t update for around an hour, the last entry mentioned about custom field name conflicts. Looking in the log file it was just repeating the following messages:
Received serializer callback: 4
Waiting for Job to be Processed. percentage complete: 0
Time to execute P12ProjectUpgrader::SerializerCallBack(): 0 ms
After looking in Project Server 2007 PWA it appeared that there was an issue with the queue service as the jobs were waiting to be processed. After a restart of the Project Server Queue service, the jobs processed though the queue and the migration then progressed and completed successfully.