diff --git a/index.js b/index.js
index ef7d22a..594020d 100755
--- a/index.js
+++ b/index.js
@@ -1,9 +1,7 @@
-'use strict'
+import {S3Client, GetObjectCommand} from "@aws-sdk/client-s3";
+import {Upload} from '@aws-sdk/lib-storage';
+import Sharp from 'sharp';
 
-
-const AWS = require('aws-sdk');
-const S3 = new AWS.S3({signatureVersion: 'v4'});
-const Sharp = require('sharp');
 const PathPattern = /(.*\/)?(.*)\/(.*)/;
 
 // parameters
@@ -12,10 +10,18 @@ const WHITELIST = process.env.WHITELIST
     ? Object.freeze(process.env.WHITELIST.split(' '))
     : null;
 
+const s3Client = new S3Client();
+
+export const handler = async (event) => {
+    const path = event.queryStringParameters?.path;
+    if (!path) {
+        return errorResponse('Parameter "?path=" is empty or missing');
+    }
 
-exports.handler = async (event) => {
-    const path = event.queryStringParameters.path;
     const parts = PathPattern.exec(path);
+    if (!parts || !parts[2] || !parts[3]) {
+        return errorResponse('Parameter "?path=" should look like: path/150x150_max/image.jpg');
+    }
     const dir = parts[1] || '';
     const resizeOption = parts[2];  // e.g. "150x150_max"
     const sizeAndAction = resizeOption.split('_');
@@ -26,27 +32,22 @@ exports.handler = async (event) => {
 
     // Whitelist validation.
     if (WHITELIST && !WHITELIST.includes(resizeOption)) {
-        return {
-            statusCode: 400,
-            body: `WHITELIST is set but does not contain the size parameter "${resizeOption}"`,
-            headers: {"Content-Type": "text/plain"}
-        };
+        return errorResponse(`WHITELIST is set but does not contain the size parameter "${resizeOption}"`, 403);
     }
 
     // Action validation.
     if (action && action !== 'max' && action !== 'min') {
-        return {
-            statusCode: 400,
-            body: `Unknown func parameter "${action}"\n` +
-                  'For query ".../150x150_func", "_func" must be either empty, "_min" or "_max"',
-            headers: {"Content-Type": "text/plain"}
-        };
+        return errorResponse(
+            `Unknown func parameter "${action}"\n` +
+            'For query ".../150x150_func", "_func" must be either empty, "_min" or "_max"'
+        );
     }
 
     try {
-        const data = await S3
-            .getObject({Bucket: BUCKET, Key: dir + filename})
-            .promise();
+        const originImage = await s3Client.send(new GetObjectCommand({
+            Bucket: BUCKET,
+            Key: dir + filename,
+        }));
 
         const width = sizes[0] === 'AUTO' ? null : parseInt(sizes[0]);
         const height = sizes[1] === 'AUTO' ? null : parseInt(sizes[1]);
@@ -62,28 +63,37 @@ exports.handler = async (event) => {
                 fit = 'cover';
                 break;
         }
-        const result = await Sharp(data.Body, {failOnError: false})
+        const sharp = Sharp({failOn: 'none'})
             .resize(width, height, {withoutEnlargement: true, fit})
-            .rotate()
-            .toBuffer();
+            .rotate();
 
-        await S3.putObject({
-            Body: result,
-            Bucket: BUCKET,
-            ContentType: data.ContentType,
-            Key: path,
-            CacheControl: 'public, max-age=86400'
-        }).promise();
+        // This does not work: await s3Client.send(new PutObjectCommand({params})
+        // Solution: https://github.com/aws/aws-sdk-js-v3/issues/1920#issuecomment-761298908
+        const upload = new Upload({
+            client: s3Client,
+            params: {
+                Bucket: BUCKET,
+                Key: path,
+                Body: originImage.Body.pipe(sharp),
+                ContentType: originImage.ContentType,
+                CacheControl: 'public, max-age=86400'
+            },
+        });
+        await upload.done();
 
         return {
             statusCode: 301,
             headers: {"Location" : `${URL}/${path}`}
         };
     } catch (e) {
-        return {
-            statusCode: e.statusCode || 400,
-            body: 'Exception: ' + e.message,
-            headers: {"Content-Type": "text/plain"}
-        };
+        return errorResponse('Exception: ' + e.message, e.statusCode || 400);
+    }
+}
+
+function errorResponse(body, statusCode = 400) {
+    return {
+        statusCode,
+        body,
+        headers: {"Content-Type": "text/plain"}
     }
 }
diff --git a/package.json b/package.json
index 078a137..374869c 100755
--- a/package.json
+++ b/package.json
@@ -1,10 +1,12 @@
 {
     "name": "s3-resizer",
-    "version": "3.0.1",
+    "version": "4.0.0",
     "dependencies": {
-        "sharp": "^0.23.3"
+        "sharp": "^0.32.0"
     },
     "devDependencies": {
-        "aws-sdk": "^2.36.0"
-    }
+        "@aws-sdk/client-s3": "^3.304.0",
+        "@aws-sdk/lib-storage": "^3.304.0"
+    },
+    "type": "module"
 }