MRP generation error: lock conflict on no wait transaction

Full error is:

General SQL error.
lock conflict on no wait transaction
update conflicts with concurrent update

This error is usually related to multiple people performing the same operation. The MRP module isn't really designed for multi-user usage (at the same time) so we recommend only having one person in at a time.  That said, we do hope to make some improvements in this area with the MRP redesign project. It isn't certain yet if the new module will be able to handle multiple users but, if it doesn't, then it will restrict user-count in the screen to a single user (rather than just popping errors).  If you don't currently have a ticket already submitted to Programmiing under that project (so that you can be notified when it's complete) then this ticket will be submitted there.

It's potential that this error could occur as a result of something other than multiple users in MRP but that's just the most common.  Regardless, the proper path forward is to log out of the software entirely and then log back in.  Then, try running MRP again.  Be sure to let support know if you are unable to resolve the error using this method (log out, log back in, just one user using MRP).