diff --git a/x-pack/packages/kbn-elastic-assistant-common/impl/data_anonymization/helpers/index.test.ts b/x-pack/packages/kbn-elastic-assistant-common/impl/data_anonymization/helpers/index.test.ts
index 02294bdd870f5..7048ab442cafa 100644
--- a/x-pack/packages/kbn-elastic-assistant-common/impl/data_anonymization/helpers/index.test.ts
+++ b/x-pack/packages/kbn-elastic-assistant-common/impl/data_anonymization/helpers/index.test.ts
@@ -123,6 +123,30 @@ describe('helpers', () => {
       expect(result).toEqual(messageContent);
     });
 
+    it('returns the original messageContent if replacements is null', () => {
+      const messageContent =
+        'User {{ user.name 3541b730-1dce-4937-b63f-0d618ea1cc5f }} added a member to the Administrators group on host {{ host.name b222e892-431e-4e4f-9295-2ba92ef9d12d }}';
+
+      const result = replaceAnonymizedValuesWithOriginalValues({
+        messageContent,
+        replacements: null, // <-- null
+      });
+
+      expect(result).toEqual(messageContent);
+    });
+
+    it('returns the original messageContent if replacements is undefined', () => {
+      const messageContent =
+        'User {{ user.name 3541b730-1dce-4937-b63f-0d618ea1cc5f }} added a member to the Administrators group on host {{ host.name b222e892-431e-4e4f-9295-2ba92ef9d12d }}';
+
+      const result = replaceAnonymizedValuesWithOriginalValues({
+        messageContent,
+        replacements: undefined, // <-- undefined
+      });
+
+      expect(result).toEqual(messageContent);
+    });
+
     it('replaces multiple occurrences of the same replacement key', () => {
       const messageContent =
         'User {{ user.name 3541b730-1dce-4937-b63f-0d618ea1cc5f }} added a member to the Administrators group on host {{ host.name b222e892-431e-4e4f-9295-2ba92ef9d12d }}, which is unusual because {{ user.name 3541b730-1dce-4937-b63f-0d618ea1cc5f }} is not a member of the Administrators group.';
diff --git a/x-pack/packages/kbn-elastic-assistant-common/impl/data_anonymization/helpers/index.ts b/x-pack/packages/kbn-elastic-assistant-common/impl/data_anonymization/helpers/index.ts
index 62f190f3d37e4..6b17b2891635a 100644
--- a/x-pack/packages/kbn-elastic-assistant-common/impl/data_anonymization/helpers/index.ts
+++ b/x-pack/packages/kbn-elastic-assistant-common/impl/data_anonymization/helpers/index.ts
@@ -40,13 +40,15 @@ export const replaceAnonymizedValuesWithOriginalValues = ({
   replacements,
 }: {
   messageContent: string;
-  replacements: Replacements;
+  replacements: Replacements | null | undefined;
 }): string =>
-  Object.keys(replacements).reduce((acc, key) => {
-    const value = replacements[key];
+  replacements != null
+    ? Object.keys(replacements).reduce((acc, key) => {
+        const value = replacements[key];
 
-    return acc.replaceAll(key, value);
-  }, messageContent);
+        return acc.replaceAll(key, value);
+      }, messageContent)
+    : messageContent;
 
 export const replaceOriginalValuesWithUuidValues = ({
   messageContent,