diff --git a/src/java/org/apache/cassandra/gms/FailureDetector.java b/src/java/org/apache/cassandra/gms/FailureDetector.java
index 49b2089297..da90efc332 100644
--- a/src/java/org/apache/cassandra/gms/FailureDetector.java
+++ b/src/java/org/apache/cassandra/gms/FailureDetector.java
@@ -326,7 +326,7 @@ public class FailureDetector implements IFailureDetector, FailureDetectorMBean
             // an error in that case.
             ClusterMetadata metadata = ClusterMetadata.current();
             if (!metadata.directory.allJoinedEndpoints().contains(ep) && !metadata.fullCMSMembers().contains(ep))
-                logger.error("Unknown endpoint: " + ep, new IllegalArgumentException("Unknown endpoint: " + ep));
+                logger.error("Unknown endpoint: " + ep, new UnknownEndpointException(ep));
         }
         return epState != null && epState.isAlive();
     }
@@ -437,6 +437,14 @@ public class FailureDetector implements IFailureDetector, FailureDetectorMBean
         sb.append("-----------------------------------------------------------------------");
         return sb.toString();
     }
+
+    public static class UnknownEndpointException extends IllegalArgumentException
+    {
+        public UnknownEndpointException(InetAddressAndPort ep)
+        {
+            super("Unknown endpoint: " + ep);
+        }
+    }
 }
 
 /*
diff --git a/src/java/org/apache/cassandra/service/accord/AccordService.java b/src/java/org/apache/cassandra/service/accord/AccordService.java
index acb4c65e8b..48c92e6296 100644
--- a/src/java/org/apache/cassandra/service/accord/AccordService.java
+++ b/src/java/org/apache/cassandra/service/accord/AccordService.java
@@ -448,35 +448,30 @@ public class AccordService implements IAccordService, Shutdownable
         if (peers.isEmpty())
             return null;
 
-        Iterator<InetAddressAndPort> iter = peers.iterator();
-        while (iter.hasNext())
+        try
         {
-            InetAddressAndPort peer = iter.next();
-            try
-            {
-                logger.info("Fetching topologies for epochs [{}, {}] from {}", from, metadata.epoch.getEpoch(), peer);
-                Invariants.require(from <= metadata.epoch.getEpoch(),
-                                   "Accord epochs should never be ahead of TCM ones, but %d was ahead of %d", from, metadata.epoch.getEpoch());
+            logger.info("Fetching topologies for epochs [{}, {}] from {}", from, metadata.epoch.getEpoch(), peers);
+            Invariants.require(from <= metadata.epoch.getEpoch(),
+                               "Accord epochs should never be ahead of TCM ones, but %d was ahead of %d", from, metadata.epoch.getEpoch());
 
-                Future<TopologyRange> futures = FetchTopologies.fetch(SharedContext.Global.instance,
-                                                                      Collections.singleton(peer),
-                                                                      from,
-                                                                      Long.MAX_VALUE);
-                TopologyRange response = futures.get();
-                logger.info("Fetched topologies {}", response);
+            Future<TopologyRange> futures = FetchTopologies.fetch(SharedContext.Global.instance,
+                                                                  peers,
+                                                                  from,
+                                                                  Long.MAX_VALUE);
+            TopologyRange response = futures.get();
+            logger.info("Fetched topologies {}", response);
 
-                // We're behind and need to catch up CMS first.
-                if (response.current > ClusterMetadata.current().epoch.getEpoch())
-                    ClusterMetadataService.instance().fetchLogFromCMS(Epoch.create(response.current));
+            // We're behind and need to catch up CMS first.
+            if (response.current > ClusterMetadata.current().epoch.getEpoch())
+                ClusterMetadataService.instance().fetchLogFromCMS(Epoch.create(response.current));
 
-                if (response.current >= from)
-                    return response;
-                metadata = ClusterMetadata.current();
-            }
-            catch (Throwable e)
-            {
-                logger.info("Failed to fetch epochs [{}, {}] from {}", from, metadata.epoch.getEpoch(), peer);
-            }
+            if (response.current >= from)
+                return response;
+            metadata = ClusterMetadata.current();
+        }
+        catch (Throwable e)
+        {
+            logger.info("Failed to fetch epochs [{}, {}] from {}", from, metadata.epoch.getEpoch(), peers);
         }
 
         // After trying to contact all peers, and retrying according to retry spec on them, we give up.
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 fbc590c942..e58e691962 100644
--- a/test/simulator/main/org/apache/cassandra/simulator/paxos/PaxosSimulation.java
+++ b/test/simulator/main/org/apache/cassandra/simulator/paxos/PaxosSimulation.java
@@ -35,6 +35,7 @@ import java.util.stream.Stream;
 import javax.annotation.Nullable;
 
 import com.google.common.base.Throwables;
+import org.apache.cassandra.gms.FailureDetector;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -85,7 +86,8 @@ public abstract class PaxosSimulation implements Simulation, ClusterActionListen
     protected Class<? extends Throwable>[] expectedExceptionsPaxos()
     {
         return (Class<? extends Throwable>[]) new Class<?>[] { RequestExecutionException.class,
-                                                               CancellationException.class };
+                                                               CancellationException.class,
+                                                               FailureDetector.UnknownEndpointException.class};
     }
 
     @SuppressWarnings("unchecked")
@@ -97,6 +99,7 @@ public abstract class PaxosSimulation implements Simulation, ClusterActionListen
                                                                CancellationException.class,
                                                                CoordinationFailed.class,
                                                                ClosedChannelException.class,
+                                                               FailureDetector.UnknownEndpointException.class,
                                                                StreamReceivedOutOfTokenRangeException.class // should always come in combination with closed channel exception
         };
     }