diff --git a/src/settings.js b/src/settings.js
index fbbe295b4..f35dd5ea7 100644
--- a/src/settings.js
+++ b/src/settings.js
@@ -410,6 +410,8 @@ function setBackupConfig(backupConfig, callback) {
     assert.strictEqual(typeof backupConfig, 'object');
     assert.strictEqual(typeof callback, 'function');
 
+    if (backupConfig.key && backupConfig.format !== 'tgz') return callback(new SettingsError(SettingsError.BAD_FIELD, 'format does not support encryption'));
+
     backups.testConfig(backupConfig, function (error) {
         if (error && error.reason === BackupsError.BAD_FIELD) return callback(new SettingsError(SettingsError.BAD_FIELD, error.message));
         if (error && error.reason === BackupsError.EXTERNAL_ERROR) return callback(new SettingsError(SettingsError.EXTERNAL_ERROR, error.message));
diff --git a/webadmin/src/views/settings.html b/webadmin/src/views/settings.html
index 15a78a3ad..263758825 100644
--- a/webadmin/src/views/settings.html
+++ b/webadmin/src/views/settings.html
@@ -179,7 +179,7 @@
 
                         <div class="form-group" ng-show="configureBackup.provider !== 'noop'">
                             <label class="control-label" for="storageFormat">Storage Format</label>
-                            <select class="form-control" id="storageFormat" ng-model="configureBackup.format" ng-options="a.value as a.name for a in formats"></select>
+                            <select class="form-control" id="storageFormat" ng-change="configureBackup.key = ''" ng-model="configureBackup.format" ng-options="a.value as a.name for a in formats"></select>
                         </div>
 
                         <div class="form-group" ng-show="configureBackup.provider !== 'noop'">