diff --git a/aws.js b/aws.js
index f138dc1..57cf0d5 100644
--- a/aws.js
+++ b/aws.js
@@ -3,12 +3,14 @@ const AWS = require('aws-sdk');
 const fs = require('fs');
 
 let accessKeyId, secretAccessKey;
+let hasCacheSupport = false;
 if (fs.existsSync('./config.json')){
   console.log('reading secrets from config.json...');
   accessKeyId = require('./config.json').accessKeyId;
   secretAccessKey = require('./config.json').secretAccessKey;
   if (accessKeyId && secretAccessKey) {
     console.log('read secrets from config.json ok');
+    hasCacheSupport = true;
   } else {
     throw new Error('read secrets from config.json failed');
   }
@@ -18,8 +20,9 @@ if (fs.existsSync('./config.json')){
   secretAccessKey = process.env.secretAccessKey;
   if (accessKeyId && secretAccessKey) {
     console.log('read secrets from env ok');
+    hasCacheSupport = true;
   } else {
-    throw new Error('read secrets from env failed');
+    console.warn('read secrets from env failed');
   }
 }
 
@@ -96,6 +99,7 @@ const deleteObject = (bucket, key) => {
 } */
 
 module.exports = {
+  hasCacheSupport,
   getObject,
   putObject,
   deleteObject,
diff --git a/routes/preview.js b/routes/preview.js
index ff476a3..ebcfa73 100644
--- a/routes/preview.js
+++ b/routes/preview.js
@@ -3,7 +3,7 @@ const http = require('http');
 const mime = require('mime');
 const fetch = require('node-fetch');
 
-const {getObject, putObject, deleteObject} = require('../aws.js');
+const {hasCacheSupport, getObject, putObject, deleteObject} = require('../aws.js');
 const browserManager = require('../browser-manager.js');
 const {renderTimeout} = require('../constants.js');
 
@@ -143,7 +143,7 @@ const _handlePreviewRequest = async (req, res) => {
     }
   })();
   const {query = {}} = u;
-  const cache = !query['nocache'];
+  const cache = hasCacheSupport && !query['nocache'];
   if (spec) {
     const {url, hash, ext, type, height, width} = spec;
     const key = `${hash}/${ext}/${type}`;