diff --git a/src/apps.js b/src/apps.js
index 070fa5575..9afd939a9 100644
--- a/src/apps.js
+++ b/src/apps.js
@@ -164,6 +164,7 @@ const appTaskManager = require('./apptaskmanager.js'),
     eventlog = require('./eventlog.js'),
     fs = require('fs'),
     Location = require('./location.js'),
+    locks = require('./locks.js'),
     logs = require('./logs.js'),
     mail = require('./mail.js'),
     manifestFormat = require('@cloudron/manifest-format'),
@@ -2789,6 +2790,9 @@ async function backup(app, auditSource) {
         })
         .catch(async (error) => {
             await eventlog.add(eventlog.ACTION_APP_BACKUP_FINISH, auditSource, { app, success: false, errorMessage: error.message });
+        })
+        .finally(async () => {
+            await locks.releaseByTaskId(taskId);
         });
 
     await eventlog.add(eventlog.ACTION_APP_BACKUP, auditSource, { app, appId: app.id, taskId });
diff --git a/src/apptaskmanager.js b/src/apptaskmanager.js
index 17c976ffb..195256a1a 100644
--- a/src/apptaskmanager.js
+++ b/src/apptaskmanager.js
@@ -57,6 +57,7 @@ async function drain() {
             .finally(async () => {
                 delete gActiveTasks[appId];
                 await locks.release(`${locks.TYPE_APP_TASK_PREFIX}${appId}`);
+                await locks.releaseByTaskId(taskId);
                 scheduler.resumeAppJobs(appId);
             });
     }
diff --git a/src/locks.js b/src/locks.js
index cc7792084..862691c80 100644
--- a/src/locks.js
+++ b/src/locks.js
@@ -105,6 +105,7 @@ async function releaseAll() {
     debug('releaseAll: all locks released');
 }
 
+// identify programming errors in tasks that forgot to clean up locks
 async function releaseByTaskId(taskId) {
     assert.strictEqual(typeof taskId, 'string');