diff --git a/test/simulator/main/org/apache/cassandra/simulator/paxos/PairOfSequencesAccordSimulation.java b/test/simulator/main/org/apache/cassandra/simulator/paxos/PairOfSequencesAccordSimulation.java
index f829da06c6..3bb911b41d 100644
--- a/test/simulator/main/org/apache/cassandra/simulator/paxos/PairOfSequencesAccordSimulation.java
+++ b/test/simulator/main/org/apache/cassandra/simulator/paxos/PairOfSequencesAccordSimulation.java
@@ -19,11 +19,9 @@
 package org.apache.cassandra.simulator.paxos;
 
 import java.nio.ByteBuffer;
-import java.nio.channels.ClosedChannelException;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
-import java.util.concurrent.CancellationException;
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.function.BiFunction;
 import java.util.function.LongSupplier;
@@ -35,8 +33,6 @@ import javax.annotation.Nullable;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import accord.coordinate.CoordinationFailed;
-import accord.coordinate.Invalidated;
 import com.carrotsearch.hppc.IntArrayList;
 import com.carrotsearch.hppc.IntHashSet;
 import com.carrotsearch.hppc.cursors.IntCursor;
@@ -52,7 +48,6 @@ import org.apache.cassandra.distributed.api.IInvokableInstance;
 import org.apache.cassandra.distributed.api.QueryResults;
 import org.apache.cassandra.distributed.api.SimpleQueryResult;
 import org.apache.cassandra.distributed.impl.Query;
-import org.apache.cassandra.exceptions.RequestExecutionException;
 import org.apache.cassandra.schema.ColumnMetadata;
 import org.apache.cassandra.schema.TableMetadata;
 import org.apache.cassandra.service.consensus.TransactionalMode;
@@ -62,7 +57,6 @@ import org.apache.cassandra.simulator.RunnableActionScheduler;
 import org.apache.cassandra.simulator.cluster.ClusterActions;
 import org.apache.cassandra.simulator.systems.SimulatedSystems;
 import org.apache.cassandra.simulator.utils.IntRange;
-import org.apache.cassandra.streaming.StreamReceivedOutOfTokenRangeException;
 
 import static org.apache.cassandra.simulator.paxos.HistoryChecker.fail;
 
@@ -159,13 +153,7 @@ public class PairOfSequencesAccordSimulation extends AbstractPairOfSequencesPaxo
     @Override
     protected Class<? extends Throwable>[] expectedExceptions()
     {
-        return (Class<? extends Throwable>[]) new Class<?>[] { CancellationException.class,
-                                                               CoordinationFailed.class,
-                                                               ClosedChannelException.class,
-                                                               Invalidated.class,
-                                                               RequestExecutionException.class,
-                                                               StreamReceivedOutOfTokenRangeException.class // should always come in combination with closed channel exception
-        };
+        return expectedExceptionsAccord();
     }
 
     @Override
diff --git a/test/simulator/main/org/apache/cassandra/simulator/paxos/PairOfSequencesPaxosSimulation.java b/test/simulator/main/org/apache/cassandra/simulator/paxos/PairOfSequencesPaxosSimulation.java
index 8592ff23b5..fbda896451 100644
--- a/test/simulator/main/org/apache/cassandra/simulator/paxos/PairOfSequencesPaxosSimulation.java
+++ b/test/simulator/main/org/apache/cassandra/simulator/paxos/PairOfSequencesPaxosSimulation.java
@@ -280,6 +280,20 @@ public class PairOfSequencesPaxosSimulation extends AbstractPairOfSequencesPaxos
         return new ModifyingOperation(operationId, instance, ANY, serialConsistency, primaryKey, historyChecker);
     }
 
+    @Override
+    protected Class<? extends Throwable>[] expectedExceptions()
+    {
+        return maybeAccord() ? expectedExceptionsAccord() : expectedExceptionsPaxos();
+    }
+
+    private boolean maybeAccord()
+    {
+        // at startup are we accord?
+        if (transactionalMode != null && transactionalMode.accordIsEnabled) return true;
+        // do we migrate to accord?
+        return clusterOptions.consensusChangeLimit > 0;
+    }
+
     @Override
     void log(@Nullable Integer primaryKey)
     {
diff --git a/test/simulator/main/org/apache/cassandra/simulator/paxos/PaxosSimulation.java b/test/simulator/main/org/apache/cassandra/simulator/paxos/PaxosSimulation.java
index 774c44a3a0..299e702a49 100644
--- a/test/simulator/main/org/apache/cassandra/simulator/paxos/PaxosSimulation.java
+++ b/test/simulator/main/org/apache/cassandra/simulator/paxos/PaxosSimulation.java
@@ -18,6 +18,7 @@
 
 package org.apache.cassandra.simulator.paxos;
 
+import java.nio.channels.ClosedChannelException;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
@@ -37,7 +38,7 @@ import com.google.common.base.Throwables;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import accord.coordinate.Invalidated;
+import accord.coordinate.CoordinationFailed;
 import org.apache.cassandra.concurrent.ExecutorFactory;
 import org.apache.cassandra.concurrent.ScheduledExecutorPlus;
 import org.apache.cassandra.distributed.Cluster;
@@ -55,6 +56,7 @@ import org.apache.cassandra.simulator.cluster.ClusterActionListener;
 import org.apache.cassandra.simulator.systems.InterceptorOfGlobalMethods;
 import org.apache.cassandra.simulator.systems.SimulatedActionCallable;
 import org.apache.cassandra.simulator.systems.SimulatedSystems;
+import org.apache.cassandra.streaming.StreamReceivedOutOfTokenRangeException;
 import org.apache.cassandra.utils.AssertionUtils;
 import org.apache.cassandra.utils.CloseableIterator;
 import org.apache.cassandra.utils.concurrent.Threads;
@@ -74,17 +76,29 @@ public abstract class PaxosSimulation implements Simulation, ClusterActionListen
 
     private static String createDescription(int[] primaryKeys, int id, String idString)
     {
-        return (primaryKeys.length == 1 ? Integer.toString(primaryKeys[0]) : Arrays.toString(primaryKeys)) + "/" + id + ": " + idString;
+        return (primaryKeys.length == 1 ? Integer.toString(primaryKeys[0]) : Arrays.toString(primaryKeys)) + '/' + id + ": " + idString;
     }
 
     @SuppressWarnings("unchecked")
-    protected Class<? extends Throwable>[] expectedExceptions()
+    protected Class<? extends Throwable>[] expectedExceptionsPaxos()
     {
         return (Class<? extends Throwable>[]) new Class<?>[] { RequestExecutionException.class,
-                                                               Invalidated.class,
                                                                CancellationException.class };
     }
 
+    @SuppressWarnings("unchecked")
+    protected Class<? extends Throwable>[] expectedExceptionsAccord()
+    {
+        return (Class<? extends Throwable>[]) new Class<?>[] { RequestExecutionException.class,
+                                                               CancellationException.class,
+                                                               CoordinationFailed.class,
+                                                               ClosedChannelException.class,
+                                                               StreamReceivedOutOfTokenRangeException.class // should always come in combination with closed channel exception
+        };
+    }
+
+    protected abstract Class<? extends Throwable>[] expectedExceptions();
+
     abstract class Operation extends SimulatedActionCallable<SimpleQueryResult> implements BiConsumer<SimpleQueryResult, Throwable>
     {
         final int[] primaryKeys;