diff --git a/lib/utils/cache.test.ts b/lib/utils/cache.test.ts
new file mode 100644
index 0000000000..1870241ffc
--- /dev/null
+++ b/lib/utils/cache.test.ts
@@ -0,0 +1,92 @@
+import { describe, expect, it, jest, afterEach, afterAll, beforeAll } from '@jest/globals';
+import wait from '@/utils/wait';
+
+beforeAll(() => {
+    process.env.CACHE_EXPIRE = '1';
+    process.env.CACHE_CONTENT_EXPIRE = '3';
+});
+
+afterEach(() => {
+    delete process.env.CACHE_TYPE;
+    jest.resetModules();
+});
+
+afterAll(() => {
+    delete process.env.CACHE_EXPIRE;
+});
+
+describe('cache', () => {
+    it('memory', async () => {
+        process.env.CACHE_TYPE = 'memory';
+        const cache = (await import('@/utils/cache')).default;
+        if (!cache.clients.memoryCache || !cache.status.available) {
+            throw new Error('Memory cache client error');
+        }
+        await cache.set('mock', undefined);
+        expect(await cache.get('mock')).toBe('');
+
+        await cache.globalCache.set('mock', undefined);
+        expect(await cache.globalCache.get('mock')).toBe('');
+        await cache.globalCache.set('mock', {
+            mock: 1,
+        });
+        expect(await cache.globalCache.get('mock')).toBe('{"mock":1}');
+    }, 10000);
+
+    it('redis', async () => {
+        process.env.CACHE_TYPE = 'redis';
+        process.env.REDIS_URL = 'redis://localhost:6380';
+        const cache = (await import('@/utils/cache')).default;
+        await wait(500);
+        if (!cache.clients.redisClient || !cache.status.available) {
+            throw new Error('Redis client error');
+        }
+        await cache.set('mock1', undefined);
+        expect(await cache.get('mock1')).toBe('');
+        await cache.set('mock2', '2');
+        await cache.set('mock2', '2');
+        expect(await cache.get('mock2')).toBe('2');
+        await cache.clients.redisClient?.quit();
+    }, 10000);
+
+    it('redis with quit', async () => {
+        process.env.CACHE_TYPE = 'redis';
+        const cache = (await import('@/utils/cache')).default;
+        if (cache.clients.redisClient) {
+            await cache.clients.redisClient.quit();
+        } else {
+            throw new Error('No redis client');
+        }
+        await cache.set('mock2', '2');
+        expect(await cache.get('mock2')).toBe(null);
+    });
+
+    it('redis with error', async () => {
+        process.env.CACHE_TYPE = 'redis';
+        process.env.REDIS_URL = 'redis://wrongpath:6379';
+        const cache = (await import('@/utils/cache')).default;
+        await cache.set('mock2', '2');
+        expect(await cache.get('mock2')).toBe(null);
+        await cache.clients.redisClient?.quit();
+    });
+
+    it('no cache', async () => {
+        process.env.CACHE_TYPE = 'NO';
+        const cache = (await import('@/utils/cache')).default;
+        await cache.set('mock2', '2');
+        expect(await cache.get('mock2')).toBe(null);
+    });
+
+    it('throws TTL key', async () => {
+        process.env.CACHE_TYPE = 'redis';
+        const cache = (await import('@/utils/cache')).default;
+
+        try {
+            await cache.get('rsshub:cacheTtl:mock');
+        } catch (error: any) {
+            expect(error.message).toContain('reserved for the internal usage');
+        } finally {
+            await cache.clients.redisClient?.quit();
+        }
+    });
+});
diff --git a/lib/utils/cache/index.ts b/lib/utils/cache/index.ts
index fee6b4e77a..422f7e3d5c 100644
--- a/lib/utils/cache/index.ts
+++ b/lib/utils/cache/index.ts
@@ -2,6 +2,7 @@ import { config } from '@/config';
 import redis from './redis';
 import memory from './memory';
 import type CacheModule from './base';
+import logger from '@/utils/logger';
 
 const globalCache: {
     get: (key: string) => Promise<string | null | undefined> | string | null | undefined;
@@ -24,7 +25,7 @@ if (config.cache.type === 'redis') {
         }
     };
     globalCache.set = cacheModule.set;
-} else {
+} else if (config.cache.type === 'memory') {
     cacheModule = memory;
     cacheModule.init();
     const { memoryCache } = cacheModule.clients;
@@ -44,6 +45,17 @@ if (config.cache.type === 'redis') {
             return memoryCache.set(key, value, { ttl: maxAge * 1000 });
         }
     };
+} else {
+    cacheModule = {
+        init: () => null,
+        get: () => null,
+        set: () => null,
+        status: {
+            available: false,
+        },
+        clients: {},
+    };
+    logger.error('Cache not available, concurrent requests are not limited. This could lead to bad behavior.');
 }
 
 // only give cache string, as the `!` condition tricky
diff --git a/lib/utils/cache/memory.ts b/lib/utils/cache/memory.ts
index b7ef70c742..395f35602c 100644
--- a/lib/utils/cache/memory.ts
+++ b/lib/utils/cache/memory.ts
@@ -3,24 +3,27 @@ import { config } from '@/config';
 import type CacheModule from './base';
 
 const status = { available: false };
-
-let memoryCache: LRUCache<any, any> | undefined;
+const clients: {
+    memoryCache?: LRUCache<any, any>;
+} = {};
 
 export default {
     init: () => {
-        memoryCache = new LRUCache({
+        clients.memoryCache = new LRUCache({
             ttl: config.cache.routeExpire * 1000,
             max: config.memory.max,
         });
         status.available = true;
     },
     get: (key: string, refresh = true) => {
-        if (key && status.available && memoryCache) {
-            let value = memoryCache.get(key, { updateAgeOnGet: refresh }) as string | undefined;
+        if (key && status.available && clients.memoryCache) {
+            let value = clients.memoryCache.get(key, { updateAgeOnGet: refresh }) as string | undefined;
             if (value) {
                 value = value + '';
             }
             return value;
+        } else {
+            return null;
         }
     },
     set: (key, value, maxAge = config.cache.contentExpire) => {
@@ -30,10 +33,10 @@ export default {
         if (typeof value === 'object') {
             value = JSON.stringify(value);
         }
-        if (key && status.available && memoryCache) {
-            return memoryCache.set(key, value, { ttl: maxAge * 1000 });
+        if (key && status.available && clients.memoryCache) {
+            return clients.memoryCache.set(key, value, { ttl: maxAge * 1000 });
         }
     },
-    clients: { memoryCache },
+    clients,
     status,
 } as CacheModule;
diff --git a/lib/utils/cache/redis.ts b/lib/utils/cache/redis.ts
index 73f0d63b73..7830b49feb 100644
--- a/lib/utils/cache/redis.ts
+++ b/lib/utils/cache/redis.ts
@@ -3,9 +3,10 @@ import Redis from 'ioredis';
 import logger from '@/utils/logger';
 import type CacheModule from './base';
 
-let redisClient: Redis | undefined;
-
 const status = { available: false };
+const clients: {
+    redisClient?: Redis;
+} = {};
 
 const getCacheTtlKey = (key: string) => {
     if (key.startsWith('rsshub:cacheTtl:')) {
@@ -16,43 +17,43 @@ const getCacheTtlKey = (key: string) => {
 
 export default {
     init: () => {
-        redisClient = new Redis(config.redis.url);
+        clients.redisClient = new Redis(config.redis.url);
 
-        const status = { available: false };
-
-        redisClient.on('error', (error) => {
+        clients.redisClient.on('error', (error) => {
             status.available = false;
             logger.error('Redis error: ', error);
         });
-        redisClient.on('end', () => {
+        clients.redisClient.on('end', () => {
             status.available = false;
         });
-        redisClient.on('connect', () => {
+        clients.redisClient.on('connect', () => {
             status.available = true;
             logger.info('Redis connected.');
         });
     },
     get: async (key: string, refresh = true) => {
-        if (key && status.available && redisClient) {
+        if (key && status.available && clients.redisClient) {
             const cacheTtlKey = getCacheTtlKey(key);
-            let [value, cacheTtl] = await redisClient.mget(key, cacheTtlKey);
+            let [value, cacheTtl] = await clients.redisClient.mget(key, cacheTtlKey);
             if (value && refresh) {
                 if (cacheTtl) {
-                    redisClient.expire(cacheTtlKey, cacheTtl);
+                    clients.redisClient.expire(cacheTtlKey, cacheTtl);
                 } else {
                     // if cacheTtl is not set, that means the cache expire time is contentExpire
                     cacheTtl = config.cache.contentExpire + '';
                     // dont save cacheTtl to Redis, as it is the default value
                     // redisClient.set(cacheTtlKey, cacheTtl, 'EX', cacheTtl);
                 }
-                redisClient.expire(key, cacheTtl);
+                clients.redisClient.expire(key, cacheTtl);
                 value = value + '';
             }
-            return value;
+            return value || '';
+        } else {
+            return null;
         }
     },
     set: (key: string, value?: string | Record<string, any>, maxAge = config.cache.contentExpire) => {
-        if (!status.available || !redisClient) {
+        if (!status.available || !clients.redisClient) {
             return;
         }
         if (!value || value === 'undefined') {
@@ -64,11 +65,11 @@ export default {
         if (key) {
             if (maxAge !== config.cache.contentExpire) {
                 // Only set cacheTtlKey if maxAge !== contentExpire
-                redisClient.set(getCacheTtlKey(key), maxAge, 'EX', maxAge);
+                clients.redisClient.set(getCacheTtlKey(key), maxAge, 'EX', maxAge);
             }
-            return redisClient.set(key, value, 'EX', maxAge); // setMode: https://redis.io/commands/set
+            return clients.redisClient.set(key, value, 'EX', maxAge); // setMode: https://redis.io/commands/set
         }
     },
-    clients: { redisClient },
+    clients,
     status,
 } as CacheModule;