Hello Hemanth,
Have you seen the below threads ?
Configuration could not be found for instance 0... | SCN
Configuration could not be found for instance x... | SCN
There are some SAP notes available for this issue.
Open the planned order and check if you can access the configuration screen, if it is missing check if there is an associated sales order, and that sales order has the configuration.
Also check if deleting the planned order in problem and re running MRP solves the issue.
Best Regards,
Ameya B.