diff --git a/pkg/operator/ceph/cluster/cluster.go b/pkg/operator/ceph/cluster/cluster.go
index 7ba602234d7b3..ebc9b1c8295b6 100755
--- a/pkg/operator/ceph/cluster/cluster.go
+++ b/pkg/operator/ceph/cluster/cluster.go
@@ -92,6 +92,13 @@ func (c *cluster) reconcileCephDaemons(rookImage string, cephVersion cephver.Cep
 	}
 	c.ClusterInfo.SetName(c.namespacedName.Name)
 
+	// Execute actions before the monitors are up and running
+	logger.Debug("monitors are about to reconcile, executing pre actions")
+	err = c.preMonStartupActions(cephVersion)
+	if err != nil {
+		return errors.Wrap(err, "failed to execute actions before reconciling the ceph monitors")
+	}
+
 	// Start the mon pods
 	controller.UpdateCondition(c.ClusterInfo.Context, c.context, c.namespacedName, cephv1.ConditionProgressing, v1.ConditionTrue, cephv1.ClusterProgressingReason, "Configuring Ceph Mons")
 	clusterInfo, err := c.mons.Start(c.ClusterInfo, rookImage, cephVersion, *c.Spec)
@@ -443,6 +450,36 @@ func (c *cluster) replaceDefaultCrushMap(newRoot string) (err error) {
 	return nil
 }
 
+// preMonStartupActions is a collection of actions to run before the monitors are reconciled.
+func (c *cluster) preMonStartupActions(cephVersion cephver.CephVersion) error {
+	// Disable the mds sanity checks for the mons due to a ceph upgrade issue
+	// for the mds to Pacific if 16.2.7 or greater.
+	if c.isUpgrade && cephVersion.IsPacific() && cephVersion.IsAtLeast(cephver.CephVersion{Major: 16, Minor: 2, Extra: 7}) {
+		if err := c.skipMDSSanityChecks(true); err != nil {
+			// If there is an error, just print it and continue. Likely there is not a
+			// negative consequence of continuing since several complex conditions must exist to hit
+			// the upgrade issue where the sanity checks need to be disabled.
+			logger.Warningf("failed to disable the mon_mds_skip_sanity. %v", err)
+		}
+	}
+	return nil
+}
+
+func (c *cluster) skipMDSSanityChecks(skip bool) error {
+	// In a running cluster disable the mds skip sanity setting during upgrades.
+	monStore := config.GetMonStore(c.context, c.ClusterInfo)
+	if skip {
+		if err := monStore.Set("mon", "mon_mds_skip_sanity", "1"); err != nil {
+			return err
+		}
+	} else {
+		if err := monStore.Delete("mon", "mon_mds_skip_sanity"); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
 // postMonStartupActions is a collection of actions to run once the monitors are up and running
 // It gets executed right after the main mon Start() method
 // Basically, it is executed between the monitors and the manager sequence
@@ -464,6 +501,15 @@ func (c *cluster) postMonStartupActions() error {
 		return errors.Wrap(err, "failed to enable Ceph messenger version 2")
 	}
 
+	// Always ensure the skip mds sanity checks setting is cleared, for all Pacific deployments
+	if c.ClusterInfo.CephVersion.IsPacific() {
+		if err := c.skipMDSSanityChecks(false); err != nil {
+			// If there is an error, just print it and continue. We can just try again
+			// at the next reconcile.
+			logger.Warningf("failed to re-enable the mon_mds_skip_sanity. %v", err)
+		}
+	}
+
 	crushRoot := client.GetCrushRootFromSpec(c.Spec)
 	if crushRoot != "default" {
 		// Remove the root=default and replicated_rule which are created by
diff --git a/pkg/operator/ceph/cluster/cluster_test.go b/pkg/operator/ceph/cluster/cluster_test.go
index c60caab5f7776..cdbef0528dd52 100644
--- a/pkg/operator/ceph/cluster/cluster_test.go
+++ b/pkg/operator/ceph/cluster/cluster_test.go
@@ -19,11 +19,17 @@ package cluster
 
 import (
 	"testing"
+	"time"
 
+	"github.com/pkg/errors"
 	cephv1 "github.com/rook/rook/pkg/apis/ceph.rook.io/v1"
 	"github.com/rook/rook/pkg/clusterd"
 	"github.com/rook/rook/pkg/daemon/ceph/client"
+	cephclient "github.com/rook/rook/pkg/daemon/ceph/client"
+	cephver "github.com/rook/rook/pkg/operator/ceph/version"
 	testop "github.com/rook/rook/pkg/operator/test"
+	exectest "github.com/rook/rook/pkg/util/exec/test"
+	"github.com/stretchr/testify/assert"
 )
 
 func TestPreClusterStartValidation(t *testing.T) {
@@ -69,3 +75,77 @@ func TestPreClusterStartValidation(t *testing.T) {
 		})
 	}
 }
+
+func TestPreMonChecks(t *testing.T) {
+	executor := &exectest.MockExecutor{}
+	context := &clusterd.Context{Executor: executor}
+	setSkipSanity := false
+	unsetSkipSanity := false
+	executor.MockExecuteCommandWithTimeout = func(timeout time.Duration, command string, args ...string) (string, error) {
+		logger.Infof("Command: %s %v", command, args)
+		if args[0] == "config" {
+			if args[1] == "set" {
+				setSkipSanity = true
+				assert.Equal(t, "mon", args[2])
+				assert.Equal(t, "mon_mds_skip_sanity", args[3])
+				assert.Equal(t, "1", args[4])
+				return "", nil
+			}
+			if args[1] == "rm" {
+				unsetSkipSanity = true
+				assert.Equal(t, "mon", args[2])
+				assert.Equal(t, "mon_mds_skip_sanity", args[3])
+				return "", nil
+			}
+		}
+		return "", errors.Errorf("unexpected ceph command %q", args)
+	}
+	c := cluster{context: context, ClusterInfo: cephclient.AdminTestClusterInfo("cluster")}
+
+	t.Run("no upgrade", func(t *testing.T) {
+		v := cephver.CephVersion{Major: 16, Minor: 2, Extra: 7}
+		c.isUpgrade = false
+		err := c.preMonStartupActions(v)
+		assert.NoError(t, err)
+		assert.False(t, setSkipSanity)
+		assert.False(t, unsetSkipSanity)
+	})
+
+	t.Run("upgrade below version", func(t *testing.T) {
+		setSkipSanity = false
+		unsetSkipSanity = false
+		v := cephver.CephVersion{Major: 16, Minor: 2, Extra: 6}
+		c.isUpgrade = true
+		err := c.preMonStartupActions(v)
+		assert.NoError(t, err)
+		assert.False(t, setSkipSanity)
+		assert.False(t, unsetSkipSanity)
+	})
+
+	t.Run("upgrade to applicable version", func(t *testing.T) {
+		setSkipSanity = false
+		unsetSkipSanity = false
+		v := cephver.CephVersion{Major: 16, Minor: 2, Extra: 7}
+		c.isUpgrade = true
+		err := c.preMonStartupActions(v)
+		assert.NoError(t, err)
+		assert.True(t, setSkipSanity)
+		assert.False(t, unsetSkipSanity)
+
+		// This will be called during the post mon checks
+		err = c.skipMDSSanityChecks(false)
+		assert.NoError(t, err)
+		assert.True(t, unsetSkipSanity)
+	})
+
+	t.Run("upgrade to quincy", func(t *testing.T) {
+		setSkipSanity = false
+		unsetSkipSanity = false
+		v := cephver.CephVersion{Major: 17, Minor: 2, Extra: 0}
+		c.isUpgrade = true
+		err := c.preMonStartupActions(v)
+		assert.NoError(t, err)
+		assert.False(t, setSkipSanity)
+		assert.False(t, unsetSkipSanity)
+	})
+}