I am receiving this error while releasing a new MRP job. I have tried clearing the user’s Epicor session and made sure their personalizations are cleared out. But we continue to receive this error. Different users too. We tried creating a whole new job, but the same error message keeps showing up. Any help or suggestions on this are appreciated.
If this is the only job you have throwing this error, I’d suggest digging into the job details to see if there’s something wrong with it.
Example: I had random scheduling failures. Turns out users were fat-finger-double-adding resource groups to ops occasionally, which was didn’t cause an issue (beyond double booking) when we have 2 or more resources in a group, but throws a hard error when there’s only 1.
It is the only job. I checked the job set up and the BOM details. It is set up how we usually set up our MRP jobs. Nothing out of the ordinary. There is no duplication on resource groups either. 
The error was showing up because the labor resource groups were not populating on the operations on the job which was not letting the scheduling go through. Our part revision was set up for a different site than the one in which the job was being set up. Updating the labor resource group on the job fixed the issue.