diff --git a/packages/unraid-api-plugin-connect/src/service/graphql.client.ts b/packages/unraid-api-plugin-connect/src/service/graphql.client.ts
index cac26a869..506563e0b 100644
--- a/packages/unraid-api-plugin-connect/src/service/graphql.client.ts
+++ b/packages/unraid-api-plugin-connect/src/service/graphql.client.ts
@@ -184,7 +184,7 @@ export class MothershipGraphqlClientService implements OnModuleInit, OnModuleDes
      * Check if an error is an invalid API key error
      */
     private isInvalidApiKeyError(error: unknown): boolean {
-        return error instanceof Error && error.message.includes('API Key Invalid');
+        return typeof error === 'object' && error !== null && 'message' in error && typeof error.message === 'string' && error.message.includes('API Key Invalid');
     }
 
     /**
diff --git a/packages/unraid-api-plugin-connect/src/test/graphql.client.test.ts b/packages/unraid-api-plugin-connect/src/test/graphql.client.test.ts
new file mode 100644
index 000000000..381ef7435
--- /dev/null
+++ b/packages/unraid-api-plugin-connect/src/test/graphql.client.test.ts
@@ -0,0 +1,160 @@
+import { beforeEach, describe, expect, it, vi } from 'vitest';
+
+import { MothershipGraphqlClientService } from '../service/graphql.client.js';
+import { MinigraphStatus } from '../model/connect-config.model.js';
+
+// Mock only the WebSocket client creation, not the Apollo Client error handling
+vi.mock('graphql-ws', () => ({
+    createClient: vi.fn(),
+}));
+
+// Mock WebSocket to avoid actual network connections
+vi.mock('ws', () => ({
+    WebSocket: vi.fn().mockImplementation(() => ({})),
+}));
+
+describe('MothershipGraphqlClientService', () => {
+    let service: MothershipGraphqlClientService;
+    let mockConfigService: any;
+    let mockConnectionService: any;
+    let mockEventEmitter: any;
+    let mockWsClient: any;
+
+    beforeEach(async () => {
+        vi.clearAllMocks();
+
+        mockConfigService = {
+            getOrThrow: vi.fn((key: string) => {
+                switch (key) {
+                    case 'API_VERSION':
+                        return '4.8.0+test';
+                    case 'MOTHERSHIP_GRAPHQL_LINK':
+                        return 'https://mothership.unraid.net/ws';
+                    default:
+                        throw new Error(`Unknown config key: ${key}`);
+                }
+            }),
+            set: vi.fn(),
+        };
+
+        mockConnectionService = {
+            getIdentityState: vi.fn().mockReturnValue({ isLoaded: true }),
+            getWebsocketConnectionParams: vi.fn().mockReturnValue({}),
+            getMothershipWebsocketHeaders: vi.fn().mockReturnValue({}),
+            getConnectionState: vi.fn().mockReturnValue({ status: MinigraphStatus.CONNECTED }),
+            setConnectionStatus: vi.fn(),
+            receivePing: vi.fn(),
+        };
+
+        mockEventEmitter = {
+            emit: vi.fn(),
+        };
+
+        mockWsClient = {
+            on: vi.fn().mockReturnValue(() => {}),
+            terminate: vi.fn(),
+            dispose: vi.fn().mockResolvedValue(undefined),
+        };
+
+        // Mock the createClient function
+        const { createClient } = await import('graphql-ws');
+        vi.mocked(createClient).mockReturnValue(mockWsClient as any);
+
+        service = new MothershipGraphqlClientService(
+            mockConfigService as any,
+            mockConnectionService as any,
+            mockEventEmitter as any
+        );
+    });
+
+    describe('isInvalidApiKeyError', () => {
+        it.each([
+            {
+                description: 'standard API key error',
+                error: { message: 'API Key Invalid with error No user found' },
+                expected: true,
+            },
+            {
+                description: 'simple API key error',
+                error: { message: 'API Key Invalid' },
+                expected: true,
+            },
+            {
+                description: 'API key error within other text',
+                error: { message: 'Something else API Key Invalid something' },
+                expected: true,
+            },
+            {
+                description: 'malformed GraphQL error with API key message',
+                error: {
+                    message: '"error" message expects the \'payload\' property to be an array of GraphQL errors, but got "API Key Invalid with error No user found"',
+                },
+                expected: true,
+            },
+            {
+                description: 'non-API key error',
+                error: { message: 'Network connection failed' },
+                expected: false,
+            },
+            {
+                description: 'null error',
+                error: null,
+                expected: false,
+            },
+            {
+                description: 'empty error object',
+                error: {},
+                expected: false,
+            },
+        ])('should identify $description correctly', ({ error, expected }) => {
+            const isInvalidApiKeyError = (service as any).isInvalidApiKeyError.bind(service);
+            expect(isInvalidApiKeyError(error)).toBe(expected);
+        });
+    });
+
+    describe('client lifecycle', () => {
+        it('should return null client when identity state is not valid', () => {
+            mockConnectionService.getIdentityState.mockReturnValue({ isLoaded: false });
+
+            const client = service.getClient();
+
+            expect(client).toBeNull();
+        });
+
+        it('should return client when identity state is valid', () => {
+            mockConnectionService.getIdentityState.mockReturnValue({ isLoaded: true });
+
+            // Since we're not mocking Apollo Client, this will create a real client
+            // We just want to verify the state check works
+            const client = service.getClient();
+            
+            // The client should either be null (if not created yet) or an Apollo client instance
+            // The key is that it doesn't throw an error when state is valid
+            expect(() => service.getClient()).not.toThrow();
+        });
+    });
+
+    describe('sendQueryResponse', () => {
+        it('should handle null client gracefully', async () => {
+            // Make identity state invalid so getClient returns null
+            mockConnectionService.getIdentityState.mockReturnValue({ isLoaded: false });
+
+            const result = await service.sendQueryResponse('test-sha256', {
+                data: { test: 'data' },
+            });
+
+            // Should not throw and should return undefined when client is null
+            expect(result).toBeUndefined();
+        });
+    });
+
+    describe('configuration', () => {
+        it('should get API version from config', () => {
+            expect(service.apiVersion).toBe('4.8.0+test');
+        });
+
+        it('should get mothership GraphQL link from config', () => {
+            expect(service.mothershipGraphqlLink).toBe('https://mothership.unraid.net/ws');
+        });
+    });
+});
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