The current implementation of Signature Constraints enforces a "hash-based" strictness check upon verifying and validating transactions with input states constrained by different versions of the same Signed CorDapp (signed by the same public key).
The following exception is observed when violating this condition:
This strictness control requires every Node in a network to install every Version of a Signed CorDapp to consumed older versioned states.
This story proposed relaxing the above control such that any Node consuming a transaction with older versioned signature-contrained inputs will trust those states if the Signing Key of these matches the Signing Key of the latest installed Version of that same CorDapp on a node.
This story was raised as a follow-up to the Corda 4.0 QA Test: