diff --git a/public/app/core/utils/dag.test.ts b/public/app/core/utils/dag.test.ts
index ee3feaa27e7..d1d7f539d27 100644
--- a/public/app/core/utils/dag.test.ts
+++ b/public/app/core/utils/dag.test.ts
@@ -122,5 +122,9 @@ describe('Directed acyclic graph', () => {
       expect(() => dag.link('A', 'B')).toThrow('cannot link A to B since it would create a cycle');
       expect(() => dag.link('A', 'E')).toThrow('cannot link A to E since it would create a cycle');
     });
+
+    it('should return undefined for unknown node id', () => {
+      expect(dag.getNode('404')).toBeUndefined();
+    });
   });
 });
diff --git a/public/app/core/utils/dag.ts b/public/app/core/utils/dag.ts
index c4e84f520ac..c5ecbd5410c 100644
--- a/public/app/core/utils/dag.ts
+++ b/public/app/core/utils/dag.ts
@@ -252,7 +252,7 @@ export class Graph {
     return new Edge();
   }
 
-  getNode(name: string): Node {
+  getNode(name: string): Node | undefined {
     return this.nodes[name];
   }
 }
diff --git a/public/app/features/alerting/unified/components/expressions/Expression.tsx b/public/app/features/alerting/unified/components/expressions/Expression.tsx
index 1369da58299..8284061a208 100644
--- a/public/app/features/alerting/unified/components/expressions/Expression.tsx
+++ b/public/app/features/alerting/unified/components/expressions/Expression.tsx
@@ -3,7 +3,15 @@ import { uniqueId } from 'lodash';
 import { FC, useCallback, useState } from 'react';
 import { useFormContext } from 'react-hook-form';
 
-import { DataFrame, GrafanaTheme2, LoadingState, PanelData, dateTimeFormat, isTimeSeriesFrames } from '@grafana/data';
+import {
+  CoreApp,
+  DataFrame,
+  GrafanaTheme2,
+  LoadingState,
+  PanelData,
+  dateTimeFormat,
+  isTimeSeriesFrames,
+} from '@grafana/data';
 import { Alert, AutoSizeInput, Button, IconButton, Stack, Text, clearButtonStyles, useStyles2 } from '@grafana/ui';
 import { ClassicConditions } from 'app/features/expressions/components/ClassicConditions';
 import { Math } from 'app/features/expressions/components/Math';
@@ -95,7 +103,15 @@ export const Expression: FC<ExpressionProps> = ({
           return <Math onChange={onChangeQuery} query={query} labelWidth={'auto'} onRunQuery={() => {}} />;
 
         case ExpressionQueryType.reduce:
-          return <Reduce onChange={onChangeQuery} refIds={availableRefIds} labelWidth={'auto'} query={query} />;
+          return (
+            <Reduce
+              onChange={onChangeQuery}
+              refIds={availableRefIds}
+              labelWidth={'auto'}
+              app={CoreApp.UnifiedAlerting}
+              query={query}
+            />
+          );
 
         case ExpressionQueryType.resample:
           return <Resample onChange={onChangeQuery} query={query} labelWidth={'auto'} refIds={availableRefIds} />;
diff --git a/public/app/features/alerting/unified/components/rule-editor/dag.test.ts b/public/app/features/alerting/unified/components/rule-editor/dag.test.ts
index 513d41abffe..914420e5b06 100644
--- a/public/app/features/alerting/unified/components/rule-editor/dag.test.ts
+++ b/public/app/features/alerting/unified/components/rule-editor/dag.test.ts
@@ -56,21 +56,21 @@ describe('working with dag', () => {
       dag.getNode('D');
     }).not.toThrow();
 
-    expect(dag.getNode('A').inputEdges).toHaveLength(0);
-    expect(dag.getNode('A').outputEdges).toHaveLength(0);
+    expect(dag.getNode('A')!.inputEdges).toHaveLength(0);
+    expect(dag.getNode('A')!.outputEdges).toHaveLength(0);
 
-    expect(dag.getNode('B').inputEdges).toHaveLength(0);
-    expect(dag.getNode('B').outputEdges).toHaveLength(2);
-    expect(dag.getNode('B').outputEdges[0].outputNode).toHaveProperty('name', 'C');
-    expect(dag.getNode('B').outputEdges[1].outputNode).toHaveProperty('name', 'D');
+    expect(dag.getNode('B')!.inputEdges).toHaveLength(0);
+    expect(dag.getNode('B')!.outputEdges).toHaveLength(2);
+    expect(dag.getNode('B')!.outputEdges[0].outputNode).toHaveProperty('name', 'C');
+    expect(dag.getNode('B')!.outputEdges[1].outputNode).toHaveProperty('name', 'D');
 
-    expect(dag.getNode('C').inputEdges).toHaveLength(1);
-    expect(dag.getNode('C').inputEdges[0].inputNode).toHaveProperty('name', 'B');
-    expect(dag.getNode('C').outputEdges).toHaveLength(0);
+    expect(dag.getNode('C')!.inputEdges).toHaveLength(1);
+    expect(dag.getNode('C')!.inputEdges[0].inputNode).toHaveProperty('name', 'B');
+    expect(dag.getNode('C')!.outputEdges).toHaveLength(0);
 
-    expect(dag.getNode('D').inputEdges).toHaveLength(1);
-    expect(dag.getNode('D').inputEdges[0].inputNode).toHaveProperty('name', 'B');
-    expect(dag.getNode('D').outputEdges).toHaveLength(0);
+    expect(dag.getNode('D')!.inputEdges).toHaveLength(1);
+    expect(dag.getNode('D')!.inputEdges[0].inputNode).toHaveProperty('name', 'B');
+    expect(dag.getNode('D')!.outputEdges).toHaveLength(0);
   });
 
   test('data queries cannot have references', () => {
diff --git a/public/app/features/alerting/unified/components/rule-editor/dag.ts b/public/app/features/alerting/unified/components/rule-editor/dag.ts
index 4900ea70025..51d519854f5 100644
--- a/public/app/features/alerting/unified/components/rule-editor/dag.ts
+++ b/public/app/features/alerting/unified/components/rule-editor/dag.ts
@@ -66,6 +66,9 @@ export const getDescendants = memoize(_getDescendants, (refId, graph) => refId +
 
 export function _getOriginsOfRefId(refId: string, graph: Graph): string[] {
   const node = graph.getNode(refId);
+  if (!node) {
+    return [];
+  }
 
   const origins: Node[] = [];
 
@@ -92,6 +95,10 @@ export function _getOriginsOfRefId(refId: string, graph: Graph): string[] {
 // get all children (and children's children etc) from a given node
 export function _getDescendants(refId: string, graph: Graph): string[] {
   const node = graph.getNode(refId);
+  if (!node) {
+    return [];
+  }
+
   const descendants: Node[] = [];
 
   // recurse through "node > outputEdges > outputNode"
diff --git a/public/app/features/expressions/ExpressionQueryEditor.tsx b/public/app/features/expressions/ExpressionQueryEditor.tsx
index 6cf394e2ef1..fdb6c9b7343 100644
--- a/public/app/features/expressions/ExpressionQueryEditor.tsx
+++ b/public/app/features/expressions/ExpressionQueryEditor.tsx
@@ -58,7 +58,7 @@ function useExpressionsCache() {
 }
 
 export function ExpressionQueryEditor(props: Props) {
-  const { query, queries, onRunQuery, onChange } = props;
+  const { query, queries, onRunQuery, onChange, app } = props;
   const { getCachedExpression, setCachedExpression } = useExpressionsCache();
 
   useEffect(() => {
@@ -83,7 +83,7 @@ export function ExpressionQueryEditor(props: Props) {
         return <Math onChange={onChange} query={query} labelWidth={labelWidth} onRunQuery={onRunQuery} />;
 
       case ExpressionQueryType.reduce:
-        return <Reduce refIds={refIds} onChange={onChange} labelWidth={labelWidth} query={query} />;
+        return <Reduce refIds={refIds} onChange={onChange} labelWidth={labelWidth} query={query} app={app} />;
 
       case ExpressionQueryType.resample:
         return <Resample query={query} labelWidth={labelWidth} onChange={onChange} refIds={refIds} />;
diff --git a/public/app/features/expressions/components/Reduce.tsx b/public/app/features/expressions/components/Reduce.tsx
index 6793b32af50..d6d203e52fd 100644
--- a/public/app/features/expressions/components/Reduce.tsx
+++ b/public/app/features/expressions/components/Reduce.tsx
@@ -1,19 +1,20 @@
 import * as React from 'react';
 
-import { SelectableValue } from '@grafana/data';
-import { InlineField, InlineFieldRow, Input, Select, Alert } from '@grafana/ui';
+import { CoreApp, SelectableValue } from '@grafana/data';
+import { Alert, InlineField, InlineFieldRow, Input, Select, TextLink } from '@grafana/ui';
 import { Trans, t } from 'app/core/internationalization';
 
 import { ExpressionQuery, ExpressionQuerySettings, ReducerMode, reducerModes, reducerTypes } from '../types';
 
 interface Props {
+  app?: CoreApp;
   labelWidth?: number | 'auto';
   refIds: Array<SelectableValue<string>>;
   query: ExpressionQuery;
   onChange: (query: ExpressionQuery) => void;
 }
 
-export const Reduce = ({ labelWidth = 'auto', onChange, refIds, query }: Props) => {
+export const Reduce = ({ labelWidth = 'auto', onChange, app, refIds, query }: Props) => {
   const reducer = reducerTypes.find((o) => o.value === query.reducer);
 
   const onRefIdChange = (value: SelectableValue<string>) => {
@@ -72,22 +73,21 @@ export const Reduce = ({ labelWidth = 'auto', onChange, refIds, query }: Props)
     );
   };
 
+  // for Alerting we really don't want to add additional confusing messages that would be unhelpful to the majority of our users
   const strictModeNotification = () => {
-    if (mode !== ReducerMode.Strict) {
+    const isWithinAlerting = app === CoreApp.UnifiedAlerting;
+    if (mode !== ReducerMode.Strict || isWithinAlerting) {
       return null;
     }
+
     return (
       <Alert title={t('reduce.strictMode.title', 'Strict Mode Behaviour')} severity="info">
         <Trans i18nKey="reduce.strictMode.description">
           When <code>Reduce Strict mode</code> is used, the <code>fill(null)</code> function (InfluxQL) will result in{' '}
           <code>NaN</code>.{' '}
-          <a
-            href="https://grafana.com/docs/grafana/latest/panels-visualizations/query-transform-data/expression-queries/#sum"
-            target="_blank"
-            rel="noopener noreferrer"
-          >
+          <TextLink href="https://grafana.com/docs/grafana/latest/panels-visualizations/query-transform-data/expression-queries/#reduction-modes">
             See the documentation for more details.
-          </a>
+          </TextLink>
         </Trans>
       </Alert>
     );