diff --git a/src/storage/s3.js b/src/storage/s3.js
index 12173e860..c6c80a413 100644
--- a/src/storage/s3.js
+++ b/src/storage/s3.js
@@ -561,7 +561,7 @@ async function testConfig(apiConfig) {
 
     const putParams = {
         Bucket: apiConfig.bucket,
-        Key: path.join(apiConfig.prefix, 'cloudron-testfile'),
+        Key: path.join(apiConfig.prefix, 'snapshot/cloudron-testfile'),
         Body: 'testcontent'
     };
 
@@ -569,9 +569,18 @@ async function testConfig(apiConfig) {
     const [putError] = await safe(s3.putObject(putParams).promise());
     if (putError) throw new BoxError(BoxError.EXTERNAL_ERROR, `Error put object cloudron-testfile. Message: ${putError.message} HTTP Code: ${putError.code}`);
 
+    const listParams = {
+        Bucket: apiConfig.bucket,
+        Prefix: path.join(apiConfig.prefix, 'snapshot'),
+        MaxKeys: 1
+    };
+
+    const [listError] = await safe(s3.listObjects(listParams).promise());
+    if (listError) throw new BoxError(BoxError.EXTERNAL_ERROR, `Error listing objects. Message: ${listError.message} HTTP Code: ${listError.code}`);
+
     const delParams = {
         Bucket: apiConfig.bucket,
-        Key: path.join(apiConfig.prefix, 'cloudron-testfile')
+        Key: path.join(apiConfig.prefix, 'snapshot/cloudron-testfile')
     };
 
     const [delError] = await safe(s3.deleteObject(delParams).promise());