diff --git a/src/backups.js b/src/backups.js
index 15b556dc9..f0b404e4c 100644
--- a/src/backups.js
+++ b/src/backups.js
@@ -252,12 +252,14 @@ function sync(backupConfig, backupId, dataDir, callback) {
 
         var retryCount = 0;
         async.retry({ times: 5, interval: 20000 }, function (retryCallback) {
+            retryCallback = once(retryCallback); // protect again upload() erroring much later after read stream error
+
             ++retryCount;
             debug(`${task.operation} ${task.path} try ${retryCount}`);
             if (task.operation === 'add') {
                 setBackupProgress(`Adding ${task.path}`);
                 var stream = fs.createReadStream(path.join(dataDir, task.path));
-                stream.on('error', function () { return retryCallback(); }); // ignore error if file disappears
+                stream.on('error', function (error) { setBackupProgress(`read stream error for ${task.path}: ${error.message}`); retryCallback(); }); // ignore error if file disappears
                 api(backupConfig.provider).upload(backupConfig, backupFilePath, stream, retryCallback);
             }
         }, iteratorCallback);
@@ -295,8 +297,6 @@ function upload(backupId, format, dataDir, callback) {
     assert.strictEqual(typeof dataDir, 'string');
     assert.strictEqual(typeof callback, 'function');
 
-    callback = once(callback);
-
     debug('upload: id %s format %s dataDir %s', backupId, format, dataDir);
 
     settings.getBackupConfig(function (error, backupConfig) {
@@ -304,6 +304,8 @@ function upload(backupId, format, dataDir, callback) {
 
         if (format === 'tgz') {
             async.retry({ times: 5, interval: 20000 }, function (retryCallback) {
+                retryCallback = once(retryCallback); // protect again upload() erroring much later after tar stream error
+
                 var tarStream = createTarPackStream(dataDir, backupConfig.key || null);
                 tarStream.on('error', retryCallback); // already returns BackupsError
 
diff --git a/src/storage/interface.js b/src/storage/interface.js
index 8e31ae509..377789716 100644
--- a/src/storage/interface.js
+++ b/src/storage/interface.js
@@ -35,6 +35,7 @@ function upload(apiConfig, backupFilePath, sourceStream, callback) {
     assert.strictEqual(typeof callback, 'function');
 
     // Result: none
+    // sourceStream errors are handled upstream
 
     callback(new Error('not implemented'));
 }
diff --git a/src/storage/s3.js b/src/storage/s3.js
index 50319fa63..d99538c3b 100644
--- a/src/storage/s3.js
+++ b/src/storage/s3.js
@@ -139,7 +139,7 @@ function upload(apiConfig, backupFilePath, sourceStream, callback) {
 
         // s3.upload automatically does a multi-part upload. we set queueSize to 1 to reduce memory usage
         // uploader will buffer at most queueSize * partSize bytes into memory at any given time.
-        return s3.upload(params, { partSize: 10 * 1024 * 1024, queueSize: 1 }, function (error) {
+        s3.upload(params, { partSize: 10 * 1024 * 1024, queueSize: 1 }, function (error) {
             if (error) {
                 debug('[%s] upload: s3 upload error.', backupFilePath, error);
                 return callback(new BackupsError(BackupsError.EXTERNAL_ERROR, `Error uploading ${backupFilePath}. Message: ${error.message} HTTP Code: ${error.code}`));