diff --git a/src/lib/features/metrics/instance/metrics.test.ts b/src/lib/features/metrics/instance/metrics.test.ts
index 3ba9205b6f..07f1c4ae88 100644
--- a/src/lib/features/metrics/instance/metrics.test.ts
+++ b/src/lib/features/metrics/instance/metrics.test.ts
@@ -303,6 +303,7 @@ describe('bulk metrics', () => {
             instanceId: 'instance5678',
             environment: 'development',
             sdkVersion: 'unleash-client-java',
+            sdkType: null,
             started: '1952-03-11T12:00:00.000Z',
             interval: 15000,
         };
diff --git a/src/lib/openapi/spec/bulk-registration-schema.ts b/src/lib/openapi/spec/bulk-registration-schema.ts
index 05c5f2d57f..edc1489130 100644
--- a/src/lib/openapi/spec/bulk-registration-schema.ts
+++ b/src/lib/openapi/spec/bulk-registration-schema.ts
@@ -74,7 +74,8 @@ export const bulkRegistrationSchema = {
             description: 'The sdk type',
             example: 'backend',
             type: 'string',
-            enum: ['frontend', 'backend'],
+            enum: ['frontend', 'backend', null],
+            nullable: true,
         },
     },
     components: {
diff --git a/src/lib/types/model.ts b/src/lib/types/model.ts
index 8d3167b28f..ad5737244e 100644
--- a/src/lib/types/model.ts
+++ b/src/lib/types/model.ts
@@ -488,7 +488,7 @@ export interface IClientApp {
     platformVersion?: string;
     yggdrasilVersion?: string;
     specVersion?: string;
-    sdkType?: 'frontend' | 'backend';
+    sdkType?: 'frontend' | 'backend' | null;
 }
 
 export interface IAppFeature {