Where are my Node.js or Python app's error logs?

Start with the Passenger log

Node.js and Python applications run through Phusion Passenger.

The application screen includes a Passenger log file setting. Set it to a file inside your application root, for example:

/home/USERNAME/APPROOT/passenger.log

Replace USERNAME and APPROOT with your account and application details.

Then:

1. Save the application settings.
2. Restart the application.
3. Open the affected URL to reproduce the error.
4. Check the log file again.

Keep log files outside public_html so visitors cannot download them.

The file appears once the app writes to it.

Check the domain error log

The web server's error log may contain problems that occur before Passenger starts the application.

cPanel

1. Sign in to cPanel.
2. Open Metrics.
3. Select Errors.
4. Look for entries matching the time you reproduced the problem.

DirectAdmin

Open System Info & Files → Site summary & logs and view the domain's error log.

Most DirectAdmin servers use OpenLiteSpeed and cannot run these Passenger applications. If you are unsure which server you use, open a support ticket before troubleshooting further.

Check Python's stderr.log

Some Python applications or Passenger configurations write errors to stderr.log in the application root.

Check for:

/home/USERNAME/APPROOT/stderr.log

If the file does not exist, use the configured Passenger log and domain error log instead.

Write useful application errors

Python applications should use Python's logging module or write errors to standard error.

Node.js applications can write errors with:

console.error("An error occurred");

Avoid logging passwords, API keys, cookies or complete database connection strings.

Read logs over SSH

To display the latest 100 lines of a log:

tail -n 100 passenger.log

To watch new entries while reproducing the problem:

tail -f passenger.log

Press Ctrl+C to stop watching.

Run these commands from the application root, or provide the full path to the log.

Common errors

Log message or symptom	What to check
ModuleNotFoundError or ImportError	Activate the Python virtual environment and install the required package
Cannot find module	Install the Node.js dependencies in the correct application environment
WSGI application cannot be loaded	Check passenger_wsgi.py and its import path
Startup file not found	Check the configured startup file and application root
Permission denied	Check file and folder permissions
Database connection failed	Check the database host, name, user, password and environment variables
Application returns 500 after an update	Review recent code, dependency and environment changes
Old code still runs	Restart the application
App never starts on DirectAdmin	Ask Webway whether the server uses a compatible Apache setup

Check for the placeholder page

If the log remains empty and you see a default hosting page, check for:

public_html/index.html

A new account's placeholder index.html can be served instead of the application. Delete it only if it is the default placeholder and not part of another website.

Do not remove the Passenger configuration written to public_html/.htaccess.

Check the application limits

The default application limits are:

Resource	Default limit
Memory	2 GB
Simultaneous requests	30
Processes	90

An application may fail, restart or return an error if it exceeds an available resource. Look for memory, process or request-limit messages around the time of the failure.

Still stuck?

Open a support ticket and include:

• Your domain or application URL
• Whether the app uses Node.js or Python
• Whether you use cPanel or DirectAdmin
• The selected runtime version
• The application root and startup file
• The exact error shown in the browser
• Relevant Passenger and domain error-log entries
• The date and approximate time you reproduced the problem
• What changed immediately before the error began