diff --git a/ghost/api-version-compatibility-service/lib/APIVersionCompatibilityService.js b/ghost/api-version-compatibility-service/lib/APIVersionCompatibilityService.js
index 14c4cfc576..5ba6a99a42 100644
--- a/ghost/api-version-compatibility-service/lib/APIVersionCompatibilityService.js
+++ b/ghost/api-version-compatibility-service/lib/APIVersionCompatibilityService.js
@@ -41,10 +41,17 @@ class APIVersionCompatibilityService {
      */
     async handleMismatch({acceptVersion, contentVersion, apiKeyValue, apiKeyType, requestURL, userAgent = ''}) {
         if (!await this.versionNotificationsDataService.fetchNotification(acceptVersion)) {
+            const integration = await this.versionNotificationsDataService.getIntegration(apiKeyValue, apiKeyType);
+
+            // We couldn't find the integration
+            if (!integration) {
+                return;
+            }
+
             const {
                 name: integrationName,
                 type: integrationType
-            } = await this.versionNotificationsDataService.getIntegration(apiKeyValue, apiKeyType);
+            } = integration;
 
             // @NOTE: "internal" or "core" integrations (https://ghost.notion.site/Data-Types-e5dc54dd0078443f9afd6b2abda443c4)
             //        are maintained by Ghost team, so there is no sense notifying the instance owner about it's incompatibility.
diff --git a/ghost/api-version-compatibility-service/test/api-version-compatibility-service.test.js b/ghost/api-version-compatibility-service/test/api-version-compatibility-service.test.js
index c9087601cc..1009e6660f 100644
--- a/ghost/api-version-compatibility-service/test/api-version-compatibility-service.test.js
+++ b/ghost/api-version-compatibility-service/test/api-version-compatibility-service.test.js
@@ -184,6 +184,43 @@ describe('APIVersionCompatibilityService', function () {
         assert.equal(sendEmail.calledTwice, false);
     });
 
+    it('Does not send email when unknown integration is detected', async function () {
+        const sendEmail = sinon.spy();
+        const findOneStub = sinon.stub();
+
+        findOneStub
+            .withArgs({
+                id: 'unknown_key'
+            }, {
+                withRelated: ['integration']
+            })
+            .resolves(null);
+
+        ApiKeyModel = {
+            findOne: findOneStub
+        };
+
+        const compatibilityService = new APIVersionCompatibilityService({
+            sendEmail,
+            ApiKeyModel,
+            UserModel,
+            settingsService,
+            getSiteUrl,
+            getSiteTitle
+        });
+
+        await compatibilityService.handleMismatch({
+            acceptVersion: 'v4.5',
+            contentVersion: 'v5.1',
+            userAgent: 'GhostAdminSDK/2.4.0',
+            requestURL: 'https://amazeballsghostsite.com/ghost/api/admin/posts/dew023d9203se4',
+            apiKeyValue: 'unknown_key',
+            apiKeyType: 'content'
+        });
+
+        assert.equal(sendEmail.called, false);
+    });
+
     it('Does NOT send an email to the instance owner when "internal" or "core" integration triggered version mismatch', async function () {
         const sendEmail = sinon.spy();
         const findOneStub = sinon.stub();
diff --git a/ghost/version-notifications-data-service/lib/VersionNotificationsDataService.js b/ghost/version-notifications-data-service/lib/VersionNotificationsDataService.js
index fe73d74380..5ac3cdef80 100644
--- a/ghost/version-notifications-data-service/lib/VersionNotificationsDataService.js
+++ b/ghost/version-notifications-data-service/lib/VersionNotificationsDataService.js
@@ -57,7 +57,7 @@ class VersionNotificationsDataService {
      *
      * @param {String} key - api key identification value, it's "secret" in case of Content API key and "id" for Admin API
      * @param {String} type - one of "content" or "admin" values
-     * @returns {Promise<Object>} Integration JSON object
+     * @returns {Promise<Object | null>} Integration JSON object
      */
     async getIntegration(key, type) {
         let queryOptions = null;
@@ -69,6 +69,9 @@ class VersionNotificationsDataService {
         }
 
         const apiKey = await this.ApiKeyModel.findOne(queryOptions, {withRelated: ['integration']});
+        if (!apiKey) {
+            return null;
+        }
 
         return apiKey.relations.integration.toJSON();
     }
diff --git a/ghost/version-notifications-data-service/test/version-notificatons-data-service.test.js b/ghost/version-notifications-data-service/test/version-notificatons-data-service.test.js
index 13cbdf1edb..b036adfc99 100644
--- a/ghost/version-notifications-data-service/test/version-notificatons-data-service.test.js
+++ b/ghost/version-notifications-data-service/test/version-notificatons-data-service.test.js
@@ -190,5 +190,27 @@ describe('Version Notification Data Service', function () {
             assert.equal(integrationName, 'Tri Hita Karana');
             assert.equal(integrationType, 'core');
         });
+
+        it('Returns null when the api-key/integration is not found', async function () {
+            const ApiKeyModel = {
+                findOne: sinon
+                    .stub()
+                    .withArgs({
+                        id: 'key_id'
+                    }, {
+                        withRelated: ['integration']
+                    })
+                    .resolves(null)
+            };
+
+            const versionNotificationsDataService = new VersionNotificationsDataService({
+                UserModel: {},
+                ApiKeyModel,
+                settingsService: {}
+            });
+
+            const integration = await versionNotificationsDataService.getIntegration('key_id', 'admin');
+            assert.equal(integration, null);
+        });
     });
 });