diff --git a/node/src/integration-test-slow/kotlin/net/corda/node/flows/FlowCheckpointVersionNodeStartupCheckTest.kt b/node/src/integration-test-slow/kotlin/net/corda/node/flows/FlowCheckpointVersionNodeStartupCheckTest.kt
index 8f440c23f2..e69703c80c 100644
--- a/node/src/integration-test-slow/kotlin/net/corda/node/flows/FlowCheckpointVersionNodeStartupCheckTest.kt
+++ b/node/src/integration-test-slow/kotlin/net/corda/node/flows/FlowCheckpointVersionNodeStartupCheckTest.kt
@@ -22,13 +22,11 @@ import net.corda.testing.driver.driver
 import net.corda.testing.node.internal.assertUncompletedCheckpoints
 import net.corda.testing.node.internal.enclosedCordapp
 import org.assertj.core.api.Assertions.assertThat
-import org.junit.Ignore
 import org.junit.Test
 import java.nio.file.Path
 import kotlin.test.assertFailsWith
 
 // TraderDemoTest already has a test which checks the node can resume a flow from a checkpoint
-@Ignore("TODO JDK17: Fixme")
 class FlowCheckpointVersionNodeStartupCheckTest {
     companion object {
         val defaultCordapp = enclosedCordapp()
diff --git a/node/src/integration-test/kotlin/net/corda/node/customcheckpointserializer/DuplicateSerializerLogTest.kt b/node/src/integration-test/kotlin/net/corda/node/customcheckpointserializer/DuplicateSerializerLogTest.kt
index 21e80ace26..0e96e84d3c 100644
--- a/node/src/integration-test/kotlin/net/corda/node/customcheckpointserializer/DuplicateSerializerLogTest.kt
+++ b/node/src/integration-test/kotlin/net/corda/node/customcheckpointserializer/DuplicateSerializerLogTest.kt
@@ -9,11 +9,9 @@ import net.corda.core.utilities.getOrThrow
 import net.corda.testing.driver.driver
 import net.corda.testing.driver.logFile
 import org.assertj.core.api.Assertions
-import org.junit.Ignore
 import org.junit.Test
 import java.time.Duration
 
-@Ignore("TODO JDK17: Fixme")
 class DuplicateSerializerLogTest{
     @Test(timeout=300_000)
     fun `check duplicate serialisers are logged`() {
diff --git a/node/src/integration-test/kotlin/net/corda/node/customcheckpointserializer/DuplicateSerializerLogWithSameSerializerTest.kt b/node/src/integration-test/kotlin/net/corda/node/customcheckpointserializer/DuplicateSerializerLogWithSameSerializerTest.kt
index 00a93e212d..3608bc7a6b 100644
--- a/node/src/integration-test/kotlin/net/corda/node/customcheckpointserializer/DuplicateSerializerLogWithSameSerializerTest.kt
+++ b/node/src/integration-test/kotlin/net/corda/node/customcheckpointserializer/DuplicateSerializerLogWithSameSerializerTest.kt
@@ -12,11 +12,9 @@ import net.corda.testing.driver.driver
 import net.corda.testing.driver.logFile
 import net.corda.testing.node.internal.enclosedCordapp
 import org.assertj.core.api.Assertions
-import org.junit.Ignore
 import org.junit.Test
 import java.time.Duration
 
-@Ignore("TODO JDK17: Fixme")
 class DuplicateSerializerLogWithSameSerializerTest {
     @Test(timeout=300_000)
     fun `check duplicate serialisers are logged not logged for the same class`() {
diff --git a/node/src/main/kotlin/net/corda/node/internal/CheckpointVerifier.kt b/node/src/main/kotlin/net/corda/node/internal/CheckpointVerifier.kt
index 052de0ab3c..c793a8904b 100644
--- a/node/src/main/kotlin/net/corda/node/internal/CheckpointVerifier.kt
+++ b/node/src/main/kotlin/net/corda/node/internal/CheckpointVerifier.kt
@@ -1,5 +1,6 @@
 package net.corda.node.internal
 
+import com.esotericsoftware.kryo.KryoException
 import net.corda.core.cordapp.Cordapp
 import net.corda.core.crypto.SecureHash
 import net.corda.core.flows.FlowLogic
@@ -42,13 +43,14 @@ object CheckpointVerifier {
             it.forEach { (_, serializedCheckpoint) ->
                 val checkpoint = try {
                     serializedCheckpoint.deserialize(checkpointSerializationContext)
-                } catch (e: ClassNotFoundException) {
-                    val message = e.message
-                    if (message != null) {
-                        throw CheckpointIncompatibleException.CordappNotInstalledException(message)
-                    } else {
-                        throw CheckpointIncompatibleException.CannotBeDeserialisedException(e)
+                } catch (e: KryoException) {
+                    if (e.cause is ClassNotFoundException) {
+                        val message = (e.cause as ClassNotFoundException).message
+                        if (message != null) {
+                            throw CheckpointIncompatibleException.CordappNotInstalledException(message)
+                        }
                     }
+                    throw CheckpointIncompatibleException.CannotBeDeserialisedException(e)
                 } catch (e: Exception) {
                     throw CheckpointIncompatibleException.CannotBeDeserialisedException(e)
                 }