diff --git a/go/test/endtoend/onlineddl/scheduler/onlineddl_scheduler_test.go b/go/test/endtoend/onlineddl/scheduler/onlineddl_scheduler_test.go
index dca084103b8..d5d7cffab08 100644
--- a/go/test/endtoend/onlineddl/scheduler/onlineddl_scheduler_test.go
+++ b/go/test/endtoend/onlineddl/scheduler/onlineddl_scheduler_test.go
@@ -646,6 +646,9 @@ func TestSchemaChange(t *testing.T) {
 			}
 		})
 	})
+	t.Run("summary: validate completed_timestamp", func(t *testing.T) {
+		onlineddl.ValidateCompletedTimestamp(t, &vtParams)
+	})
 }
 
 // testOnlineDDLStatement runs an online DDL, ALTER statement
diff --git a/go/test/endtoend/onlineddl/vrepl/onlineddl_vrepl_test.go b/go/test/endtoend/onlineddl/vrepl/onlineddl_vrepl_test.go
index 93420b0f326..118488c63b1 100644
--- a/go/test/endtoend/onlineddl/vrepl/onlineddl_vrepl_test.go
+++ b/go/test/endtoend/onlineddl/vrepl/onlineddl_vrepl_test.go
@@ -756,6 +756,9 @@ func TestSchemaChange(t *testing.T) {
 			}
 		})
 	})
+	t.Run("summary: validate completed_timestamp", func(t *testing.T) {
+		onlineddl.ValidateCompletedTimestamp(t, &vtParams)
+	})
 }
 
 func insertRow(t *testing.T) {
diff --git a/go/test/endtoend/onlineddl/vtgate_util.go b/go/test/endtoend/onlineddl/vtgate_util.go
index 86ea963465a..1b6def8ecf4 100644
--- a/go/test/endtoend/onlineddl/vtgate_util.go
+++ b/go/test/endtoend/onlineddl/vtgate_util.go
@@ -35,6 +35,14 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
+var (
+	testsStartupTime time.Time
+)
+
+func init() {
+	testsStartupTime = time.Now()
+}
+
 // VtgateExecQuery runs a query on VTGate using given query params
 func VtgateExecQuery(t *testing.T, vtParams *mysql.ConnParams, query string, expectError string) *sqltypes.Result {
 	t.Helper()
@@ -344,3 +352,68 @@ func WaitForThrottledTimestamp(t *testing.T, vtParams *mysql.ConnParams, uuid st
 	t.Error("timeout waiting for last_throttled_timestamp to have nonempty value")
 	return
 }
+
+// ValidateSequentialMigrationIDs validates that schem_migrations.id column, which is an AUTO_INCREMENT, does
+// not have gaps
+func ValidateSequentialMigrationIDs(t *testing.T, vtParams *mysql.ConnParams, shards []cluster.Shard) {
+	r := VtgateExecQuery(t, vtParams, "show vitess_migrations", "")
+	shardMin := map[string]uint64{}
+	shardMax := map[string]uint64{}
+	shardCount := map[string]uint64{}
+
+	for _, row := range r.Named().Rows {
+		id := row.AsUint64("id", 0)
+		require.NotZero(t, id)
+
+		shard := row.AsString("shard", "")
+		require.NotEmpty(t, shard)
+
+		if _, ok := shardMin[shard]; !ok {
+			shardMin[shard] = id
+			shardMax[shard] = id
+		}
+		if id < shardMin[shard] {
+			shardMin[shard] = id
+		}
+		if id > shardMax[shard] {
+			shardMax[shard] = id
+		}
+		shardCount[shard]++
+	}
+	require.NotEmpty(t, shards)
+	assert.Equal(t, len(shards), len(shardMin))
+	assert.Equal(t, len(shards), len(shardMax))
+	assert.Equal(t, len(shards), len(shardCount))
+	for shard, count := range shardCount {
+		assert.NotZero(t, count)
+		assert.Equalf(t, count, shardMax[shard]-shardMin[shard]+1, "mismatch: shared=%v, count=%v, min=%v, max=%v", shard, count, shardMin[shard], shardMax[shard])
+	}
+}
+
+// ValidateCompletedTimestamp ensures that any migration in `cancelled`, `completed`, `failed` statuses
+// has a non-nil and valid `completed_timestamp` value.
+func ValidateCompletedTimestamp(t *testing.T, vtParams *mysql.ConnParams) {
+	require.False(t, testsStartupTime.IsZero())
+	r := VtgateExecQuery(t, vtParams, "show vitess_migrations", "")
+
+	completedTimestampNumValidations := 0
+	for _, row := range r.Named().Rows {
+		migrationStatus := row.AsString("migration_status", "")
+		require.NotEmpty(t, migrationStatus)
+		switch migrationStatus {
+		case string(schema.OnlineDDLStatusComplete),
+			string(schema.OnlineDDLStatusFailed),
+			string(schema.OnlineDDLStatusCancelled):
+			{
+				assert.False(t, row["completed_timestamp"].IsNull())
+				// Also make sure the timestamp is "real", and that it is recent.
+				timestamp := row.AsString("completed_timestamp", "")
+				completedTime, err := time.Parse(sqltypes.TimestampFormat, timestamp)
+				assert.NoError(t, err)
+				assert.Greater(t, completedTime.Unix(), testsStartupTime.Unix())
+				completedTimestampNumValidations++
+			}
+		}
+	}
+	assert.NotZero(t, completedTimestampNumValidations)
+}
diff --git a/go/test/endtoend/onlineddl/vttablet_util.go b/go/test/endtoend/onlineddl/vttablet_util.go
index 4d4e88b8189..893d312d977 100644
--- a/go/test/endtoend/onlineddl/vttablet_util.go
+++ b/go/test/endtoend/onlineddl/vttablet_util.go
@@ -31,7 +31,7 @@ import (
 )
 
 // WaitForVReplicationStatus waits for a vreplication stream to be in one of given states, or timeout
-func WaitForVReplicationStatus(t *testing.T, vtParams *mysql.ConnParams, shards []cluster.Shard, uuid string, timeout time.Duration, expectStatuses ...string) (status string) {
+func WaitForVReplicationStatus(t *testing.T, vtParams *mysql.ConnParams, shards []cluster.Shard, uuid string, timeout time.Duration, expectStatuses ...string) (status string) { // nolint:revive
 
 	query, err := sqlparser.ParseAndBind("select workflow, state from _vt.vreplication where workflow=%a",
 		sqltypes.StringBindVariable(uuid),
diff --git a/go/vt/vttablet/onlineddl/executor.go b/go/vt/vttablet/onlineddl/executor.go
index 4663722983c..d64ee55e7b7 100644
--- a/go/vt/vttablet/onlineddl/executor.go
+++ b/go/vt/vttablet/onlineddl/executor.go
@@ -101,6 +101,13 @@ var vexecInsertTemplates = []string{
 		'val1', 'val2', 'val3', 'val4', 'val5', 'val6', 'val7', 'val8', 'val9', FROM_UNIXTIME(0), 'vala', 'valb'
 	)`,
 }
+var (
+	// fixCompletedTimestampDone fixes a nil `completed_tiemstamp` columns, see
+	// https://github.com/vitessio/vitess/issues/13927
+	// The fix is in release-18.0
+	// TODO: remove in release-19.0
+	fixCompletedTimestampDone bool
+)
 
 var emptyResult = &sqltypes.Result{}
 var acceptableDropTableIfExistsErrorCodes = []int{mysql.ERCantFindFile, mysql.ERNoSuchTable}
@@ -3754,13 +3761,17 @@ func (e *Executor) gcArtifacts(ctx context.Context) error {
 	e.migrationMutex.Lock()
 	defer e.migrationMutex.Unlock()
 
-	if _, err := e.execQuery(ctx, sqlFixCompletedTimestamp); err != nil {
-		// This query fixes a bug where stale migrations were marked as 'failed' without updating 'completed_timestamp'
-		// see https://github.com/vitessio/vitess/issues/8499
-		// Running this query retroactively sets completed_timestamp
-		// This 'if' clause can be removed in version v13
-		return err
+	// v18 fix. Remove in v19
+	if !fixCompletedTimestampDone {
+		if _, err := e.execQuery(ctx, sqlFixCompletedTimestamp); err != nil {
+			// This query fixes a bug where stale migrations were marked as 'cancelled' or 'failed' without updating 'completed_timestamp'
+			// Running this query retroactively sets completed_timestamp
+			// This fix is created in v18 and can be removed in v19
+			return err
+		}
+		fixCompletedTimestampDone = true
 	}
+
 	query, err := sqlparser.ParseAndBind(sqlSelectUncollectedArtifacts,
 		sqltypes.Int64BindVariable(int64((retainOnlineDDLTables).Seconds())),
 	)
diff --git a/go/vt/vttablet/onlineddl/schema.go b/go/vt/vttablet/onlineddl/schema.go
index 41449572508..833148939b0 100644
--- a/go/vt/vttablet/onlineddl/schema.go
+++ b/go/vt/vttablet/onlineddl/schema.go
@@ -133,7 +133,8 @@ const (
 			migration_uuid=%a
 	`
 	sqlUpdateMigrationStatusFailedOrCancelled = `UPDATE _vt.schema_migrations
-			SET migration_status=IF(cancelled_timestamp IS NULL, 'failed', 'cancelled')
+			SET migration_status=IF(cancelled_timestamp IS NULL, 'failed', 'cancelled'),
+			completed_timestamp=NOW(6)
 		WHERE
 			migration_uuid=%a
 	`
@@ -414,7 +415,7 @@ const (
 		SET
 			completed_timestamp=NOW()
 		WHERE
-			migration_status='failed'
+			migration_status IN ('cancelled', 'failed')
 			AND cleanup_timestamp IS NULL
 			AND completed_timestamp IS NULL
 	`