❌ Error: Can’t acquire lock for app (Node.js – Shared Hosting)

Applies To

• DirectAdmin Shared Hosting
• Node.js Applications
• Error example: Can't acquire lock for app: domains/yourdomain.com/public_html/your-node-app

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📌 Overview

This error occurs when a Node.js application becomes stuck in a locked state.
DirectAdmin uses a lock mechanism to manage Node.js processes. If an app crashes, restarts incorrectly, or is force-stopped, the lock file may not release automatically.

As a result, the control panel cannot start or manage the application.

This guide explains how to safely fix the issue without terminal/SSH access.

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🚨 Common Reasons for This Error

• Node.js app crashed unexpectedly
• App was restarted too quickly
• Browser session closed while starting/stopping app
• Server resource limit hit
• Previous lock file not cleared automatically

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✅ Solution 1: Restart the App from DirectAdmin/cPanel (Recommended First)

Step 1: Login to DirectAdmin or cPanel

• Open your hosting control panel
• Navigate to: Account Manager → Node.js Apps

Step 2: Stop the App

• Locate your Node.js application
• Click STOP
• Even if the app already shows “Stopped”, still click STOP

Step 3: Wait

• Wait 30–60 seconds
• This allows the system to release the lock automatically

Step 4: Start the App

• Click START

✔ If the app starts successfully → Issue resolved

❌ If error persists → Proceed to Solution 2

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🔥 Solution 2: Remove Lock File Manually (Most Effective)

This is the best and safest fix when terminal access is not available.

Step 1: Open File Manager

• Go to: Account Manager → File Manager

Step 2: Enable Hidden Files

• Click Settings or Options
• Enable: ☑ Show Hidden Files (dotfiles)

Step 3: Navigate to Node.js Directory

Go to:

domains/yourdomain.com/.nodejs/

⚠️ Note: The .nodejs folder is hidden by default.

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Step 4: Delete Lock Files

Inside the .nodejs folder, delete only the following if they exist:

lock
.lock
pid
pids/

✔ These files are safe to remove
❌ Do NOT delete other files

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Step 5: Restart the App

• Go back to: Account Manager → Node.js Apps
• Click START

✅ The app should now start normally.

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⚙️ Solution 3: Increase Execution Limits (Prevention)

Low execution limits can cause apps to crash and lock again.

Recommended PHP Settings

Set the following values in Select PHP Version / PHP Settings:

max_execution_time = 300
memory_limit = 512M

Where to update

Account Manager → Select PHP Version → Options

Save changes after updating.

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🛡️ Optional: Add Graceful Exit Handling (Advanced)

To prevent lock issues during restarts, add this code to your Node.js app:

process.on('SIGTERM', () => {
  process.exit(0);
});

process.on('SIGINT', () => {
  process.exit(0);
});

This ensures the app releases locks properly when stopped by DirectAdmin.

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⚠️ Important Limitations of Shared Hosting

Node.js on shared hosting has the following constraints:

• No process manager (PM2 not available)
• Limited memory & CPU
• Apps can stop unexpectedly
• Lock issues may recur under heavy load