diff --git a/pkg/services/ngalert/state/manager_test.go b/pkg/services/ngalert/state/manager_test.go
index 075f3b3a822..8ee29ab0efd 100644
--- a/pkg/services/ngalert/state/manager_test.go
+++ b/pkg/services/ngalert/state/manager_test.go
@@ -1868,7 +1868,7 @@ func TestProcessEvalResults(t *testing.T) {
 							Values:          make(map[string]*float64),
 						},
 					},
-					StartsAt:           evaluationTime.Add(20 * time.Second),
+					StartsAt:           evaluationTime.Add(30 * time.Second),
 					EndsAt:             evaluationTime.Add(50 * time.Second).Add(state.ResendDelay * 3),
 					LastEvaluationTime: evaluationTime.Add(50 * time.Second),
 					EvaluationDuration: evaluationDuration,
diff --git a/pkg/services/ngalert/state/state.go b/pkg/services/ngalert/state/state.go
index d0892db5d74..65ba71c72e2 100644
--- a/pkg/services/ngalert/state/state.go
+++ b/pkg/services/ngalert/state/state.go
@@ -198,6 +198,11 @@ func (a *State) resultError(alertRule *models.AlertRule, result eval.Result) {
 		// is unavailable or queries against the datasource returns errors, and is
 		// then resolved as soon as the datasource is available and queries return
 		// without error
+		if a.State != execErrState {
+			// Set the start time if the state changes from Alerting to Error or from
+			// Error to Alerting
+			a.StartsAt = result.EvaluatedAt
+		}
 		a.State = execErrState
 		a.setEndsAt(alertRule, result)
 	case eval.Pending: