diff --git a/core/src/main/kotlin/net/corda/core/contracts/BelongsToContract.kt b/core/src/main/kotlin/net/corda/core/contracts/BelongsToContract.kt
index def0a947fa..44b1523c7a 100644
--- a/core/src/main/kotlin/net/corda/core/contracts/BelongsToContract.kt
+++ b/core/src/main/kotlin/net/corda/core/contracts/BelongsToContract.kt
@@ -1,6 +1,7 @@
 package net.corda.core.contracts
 
 import kotlin.reflect.KClass
+import net.corda.core.contracts.TransactionVerificationException.TransactionContractConflictException
 
 /**
  * This annotation is required by any [ContractState] which needs to ensure that it is only ever processed as part of a
@@ -12,7 +13,8 @@ import kotlin.reflect.KClass
  * checked to ensure that their [ContractState]s match with their [Contract]s as specified either by this annotation, or
  * by their inner/outer class relationship.
  *
- * The transaction will write a warning to the log if any mismatch is detected.
+ * The transaction will write a warning to the log (for corDapps with a target version less than 4) or
+ * fail with a [TransactionContractConflictException] if any mismatch is detected.
  *
  * @param value The class of the [Contract] to which states of the annotated [ContractState] belong.
  */
diff --git a/core/src/main/kotlin/net/corda/core/flows/NotaryError.kt b/core/src/main/kotlin/net/corda/core/flows/NotaryError.kt
index d849f29324..835f0291ab 100644
--- a/core/src/main/kotlin/net/corda/core/flows/NotaryError.kt
+++ b/core/src/main/kotlin/net/corda/core/flows/NotaryError.kt
@@ -28,7 +28,7 @@ sealed class NotaryError {
             /** Specifies which states have already been consumed in another transaction. */
             val consumedStates: Map<StateRef, StateConsumptionDetails>
     ) : NotaryError() {
-        override fun toString() = "One or more input states have already been used in other transactions. Conflicting state count: ${consumedStates.size}, consumption details:\n" +
+        override fun toString() = "One or more input states or referenced states have already been used as input states in other transactions. Conflicting state count: ${consumedStates.size}, consumption details:\n" +
                 "${consumedStates.asSequence().joinToString(",\n", limit = 5) { it.key.toString() + " -> " + it.value }}.\n" +
                 "To find out if any of the conflicting transactions have been generated by this node you can use the hashLookup Corda shell command."
     }
diff --git a/finance/contracts/build.gradle b/finance/contracts/build.gradle
index 89ac236954..77207e090a 100644
--- a/finance/contracts/build.gradle
+++ b/finance/contracts/build.gradle
@@ -39,12 +39,19 @@ task testJar(type: Jar) {
 
 jar {
     baseName 'corda-finance-contracts'
+    manifest {
+        attributes('Corda-Revision': 'n/a')
+        attributes('Corda-Vendor': 'Corda Open Source')
+    }
 }
 
 artifacts {
     testArtifacts testJar
 }
 cordapp {
+    signing {
+        enabled false
+    }
     targetPlatformVersion corda_platform_version.toInteger()
     minimumPlatformVersion 1
     contract {