The error message sounds like a resource problem.
Is there anything in the app-niku.log that would help identifying the cause?
Do the resource and team views display anything that would lead to the cause?
It should be possible to XOG read the project out with the problem.
If you try write it back to another environment the XOG client should give more descriptive error message which helps to solve the problem.
TEC468125 How do I enable Scheduler logging for Open Workbench troubleshooting?
https://comm.support.ca.com/?legacyid=TEC468125
tells how to log more details on what is happening.
Does the project open in scheduler in browser?
Martti K.