How To Fix NodeJS Selector Not Working With An Error Can't acquire lock for app

❌ Fix: "Can't Acquire Lock for an App" Error in Node.js Selector (CloudLinux)

When using CloudLinux's Node.js Selector, you might encounter the following error:

"Can't acquire lock for an app"

This typically occurs when a background process or daemon script (previously started via Node.js Selector → "Run NPM Script") continues to run in the background and holds a .lock file.

🔍 Why This Happens

• A script was started using Run NPM Script.

• That script keeps running in the background.

• It holds a lock on the app, preventing new actions like start/stop/configuration changes.

• You can’t stop it from the UI — only from the command line.

🛠️ Solution: Kill the Locking Process

✅ Step 1: Find Lock Processes

Run the following command as root, replacing username with the actual cPanel username:

You should see output similar to:

🛑 Step 2: Kill the Process Holding the Lock

Use the process ID (e.g., 123456) from the above output:

Repeat this for all listed processes that are holding lock files.

🔁 Step 3: Retry the Action in Node.js Selector

Now go back to the cPanel → Node.js Selector, and you should be able to manage the application normally (start, stop, restart, etc.).

📌 Optional Tip:

To prevent this issue in the future:

• Avoid using "Run NPM Script" to start long-running/daemon processes.

• Instead, start your app using npm start inside the terminal or integrate with PM2 or systemd for better process management.