**Build scan:**
https://gradle-enterprise.elastic.co/s/bcxstpjolnb2q/tests/:x-pack:plugin:ccr:internalClusterTest/org.elasticsearch.xpack.ccr.FollowerFailOverIT/testReadRequestsReturnLatestMappingVersion

**Reproduction line:**
```
./gradlew ':x-pack:plugin:ccr:internalClusterTest' --tests "org.elasticsearch.xpack.ccr.FollowerFailOverIT.testReadRequestsReturnLatestMappingVersion" -Dtests.seed=A75C1F0C6F541957 -Dtests.locale=fr-CA -Dtests.timezone=America/Tijuana -Druntime.java=20
```

**Applicable branches:**
8.10

**Reproduces locally?:**
Didn't try

**Failure history:**
https://gradle-enterprise.elastic.co/scans/tests?tests.container=org.elasticsearch.xpack.ccr.FollowerFailOverIT&tests.test=testReadRequestsReturnLatestMappingVersion

**Failure excerpt:**
```
com.carrotsearch.randomizedtesting.UncaughtExceptionError: Captured an uncaught exception in thread: Thread[id=498, name=elasticsearch[follower2][clusterApplierService#updateTask][T#1], state=RUNNABLE, group=TGRP-FollowerFailOverIT]

  at __randomizedtesting.SeedInfo.seed([A75C1F0C6F541957:A564CB31A58082CC]:0)

  Caused by: java.lang.AssertionError: (No message provided)

    at __randomizedtesting.SeedInfo.seed([A75C1F0C6F541957]:0)
    at org.elasticsearch.discovery.PeerFinder.closePeers(PeerFinder.java:182)
    at org.elasticsearch.cluster.coordination.Coordinator.onClusterStateApplied(Coordinator.java:415)
    at org.elasticsearch.cluster.coordination.Coordinator.lambda$handleApplyCommit$8(Coordinator.java:403)
    at org.elasticsearch.action.ActionListenerImplementations$MappedActionListener.lambda$map$0(ActionListenerImplementations.java:108)
    at org.elasticsearch.action.ActionListenerImplementations$MappedActionListener.onResponse(ActionListenerImplementations.java:89)
    at org.elasticsearch.cluster.service.ClusterApplierService$ClusterApplyActionListener.onResponse(ClusterApplierService.java:598)
    at org.elasticsearch.cluster.service.ClusterApplierService$ClusterApplyActionListener.onResponse(ClusterApplierService.java:569)
    at org.elasticsearch.cluster.service.ClusterApplierService.runTask(ClusterApplierService.java:439)
    at org.elasticsearch.cluster.service.ClusterApplierService$UpdateTask.run(ClusterApplierService.java:154)
    at org.elasticsearch.common.util.concurrent.ThreadContext$ContextPreservingRunnable.run(ThreadContext.java:916)
    at org.elasticsearch.common.util.concurrent.PrioritizedEsThreadPoolExecutor$TieBreakingPrioritizedRunnable.runAndClean(PrioritizedEsThreadPoolExecutor.java:217)
    at org.elasticsearch.common.util.concurrent.PrioritizedEsThreadPoolExecutor$TieBreakingPrioritizedRunnable.run(PrioritizedEsThreadPoolExecutor.java:183)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1144)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:642)
    at java.lang.Thread.run(Thread.java:1623)

```
server/src/main/java/org/elasticsearch/cluster/coordination/Coordinator.java
"{}: coordinator becoming CANDIDATE in term {} (was {}, lastKnownLeader was [{}])",
            method,
            getCurrentTerm(),
            mode,
            lastKnownLeader
        );
        if (mode != Mode.CANDIDATE) {
            final Mode prevMode = mode;
            mode = Mode.CANDIDATE;
            cancelActivePublication("become candidate: " + method);
            joinAccumulator.close(mode);
            joinAccumulator = joinHelper.new CandidateJoinAccumulator();
            peerFinder.activate(coordinationState.get().getLastAcceptedState().nodes());
            clusterFormationFailureHelper.start();
            leaderHeartbeatService.stop();
            leaderChecker.setCurrentNodes(DiscoveryNodes.EMPTY_NODES);
            leaderChecker.updateLeader(null);
            followersChecker.clearCurrentNodes();
            followersChecker.updateFastResponseState(getCurrentTerm(), mode);
            lagDetector.clearTrackedNodes();
            if (prevMode == Mode.LEADER) {
                cleanMasterService();
            }
            if (applierState.nodes().getMasterNodeId() != null) {
                applierState = clusterStateWithNoMasterBlock(applierState);
                clusterApplier.onNewClusterState("becoming candidate: " + method, () -> applierState, ActionListener.noop());
            }
        }
        updateSingleNodeClusterChecker();
        preVoteCollector.update(getPreVoteResponse(), null);