Skip Navigation
Show nav
Heroku Dev Center
  • Get Started
  • Documentation
  • Changelog
  • Search
  • Get Started
    • Node.js
    • Ruby on Rails
    • Ruby
    • Python
    • Java
    • PHP
    • Go
    • Scala
    • Clojure
  • Documentation
  • Changelog
  • More
    Additional Resources
    • Home
    • Elements
    • Products
    • Pricing
    • Careers
    • Help
    • Status
    • Events
    • Podcasts
    • Compliance Center
    Heroku Blog

    Heroku Blog

    Find out what's new with Heroku on our blog.

    Visit Blog
  • Log inorSign up
View categories

Categories

  • Heroku Architecture
    • Dynos (app containers)
    • Stacks (operating system images)
    • Networking & DNS
    • Platform Policies
    • Platform Principles
  • Command Line
  • Deployment
    • Deploying with Git
    • Deploying with Docker
    • Deployment Integrations
  • Continuous Delivery
    • Continuous Integration
  • Language Support
    • Node.js
    • Ruby
      • Working with Bundler
      • Rails Support
    • Python
      • Working with Django
      • Background Jobs in Python
    • Java
      • Working with Maven
      • Java Database Operations
      • Working with Spring Boot
      • Java Advanced Topics
    • PHP
    • Go
      • Go Dependency Management
    • Scala
    • Clojure
  • Databases & Data Management
    • Heroku Postgres
      • Postgres Basics
      • Postgres Getting Started
      • Postgres Performance
      • Postgres Data Transfer & Preservation
      • Postgres Availability
      • Postgres Special Topics
    • Heroku Data For Redis
    • Apache Kafka on Heroku
    • Other Data Stores
  • Monitoring & Metrics
    • Logging
  • App Performance
  • Add-ons
    • All Add-ons
  • Collaboration
  • Security
    • App Security
    • Identities & Authentication
    • Compliance
  • Heroku Enterprise
    • Private Spaces
      • Infrastructure Networking
    • Enterprise Accounts
    • Enterprise Teams
    • Heroku Connect (Salesforce sync)
      • Heroku Connect Administration
      • Heroku Connect Reference
      • Heroku Connect Troubleshooting
    • Single Sign-on (SSO)
  • Patterns & Best Practices
  • Extending Heroku
    • Platform API
    • App Webhooks
    • Heroku Labs
    • Building Add-ons
      • Add-on Development Tasks
      • Add-on APIs
      • Add-on Guidelines & Requirements
    • Building CLI Plugins
    • Developing Buildpacks
    • Dev Center
  • Accounts & Billing
  • Troubleshooting & Support
  • Integrating with Salesforce
  • Troubleshooting & Support
  • Recovering an Offline Application

Recovering an Offline Application

English — 日本語に切り替える

Last updated February 03, 2023

Table of Contents

  • Check your application logs
  • Check your processes
  • Restart your application
  • Test using curl
  • Check application health
  • Review advice for production applications
  • Check platform status
  • Ask for help

Your application may be experiencing downtime for a number of reasons. This article will help you discover why and what you can do to remedy the problem.

Check your application logs

The first step is to check your application’s logs. Many common application errors as well as Heroku’s errors are printed to your applications logs. To view your logs, run:

$ heroku logs

Note that many frameworks, including Ruby on Rails, will serve a default error page for your application when there are errors. You can compare this to Heroku’s error page which is used when one of Heroku’s error codes is the cause of the issue.

If your logs show one of Heroku’s error codes, you should investigate the cause of this issue. Our descriptions of these errors is the best place to start.

Check your processes

Check on the current status of your process formation:

$ heroku ps

This will tell you the current state of your application’s dynos. Ensure you are running the right number of each process type (at least one) and your dynos are booting correctly.

$ heroku scale web=1

If your dynos are crashed, restarting the app can help debug the issue.

Restart your application

If the problem is not immediately present, it can be helpful to restart your application, tail your logs, and then try viewing your application in a web browser.

$ heroku restart
$ heroku logs --tail
$ heroku open

Some application issues are solved by restart. For example, your application may need to be restarted after a schema change to your database, or if recent Heroku maintenance affected your application.

Test using curl

A number of issues can be detected using curl:

$ curl -v http://example.herokuapp.com/

Testing your herokuapp.com hostname in addition to your custom domains will help determine if the issue is specific to your custom domain or your application.

Some common issues you may discover are:

  • An HTTP 500 error code indicates an error returned by your application. Check your Heroku logs for more details.

  • An HTTP 503 error code indicates a Heroku error code. Check your logs for the error code you received and reference our Heroku error code documentation for further information.

  • DNS errors (could not resolve host) should be resolved by correctly setting up your custom domain for use on Heroku. Note that alternate instructions apply if you are using SSL.

  • Certificate errors, or other errors relating to using SSL, should refer to our SSL documentation.

Check application health

Heroku provides several additional tools to check the health of your application.

  • Check heroku releases for recent changes made to your application. You can rollback to an older release if necessary.

  • A monitoring add-on like New Relic is an excellent way of keeping an eye on your application’s health. A large change in requests received or response time may indicate that you need to scale your application or migrate to a larger database.

Review advice for production applications

Your application may be affected by an issue that would best be mitigated by modifying how your Heroku application is running on the platform. Production Check is a great tool for ensuring that your app is ready to run on the platform in production.

Check platform status

An active or recent incident could cause your application to be unavailable or unstable. You should check Heroku’s status site to see if your application is affected.

Ask for help

If you are still unable to determine why your application is down, get in touch with us via our support channels.

Keep reading

  • Troubleshooting & Support

Feedback

Log in to submit feedback.

Wrong Version of Ruby or Rake in App Request Timeout

Information & Support

  • Getting Started
  • Documentation
  • Changelog
  • Compliance Center
  • Training & Education
  • Blog
  • Podcasts
  • Support Channels
  • Status

Language Reference

  • Node.js
  • Ruby
  • Java
  • PHP
  • Python
  • Go
  • Scala
  • Clojure

Other Resources

  • Careers
  • Elements
  • Products
  • Pricing

Subscribe to our monthly newsletter

Your email address:

  • RSS
    • Dev Center Articles
    • Dev Center Changelog
    • Heroku Blog
    • Heroku News Blog
    • Heroku Engineering Blog
  • Heroku Podcasts
  • Twitter
    • Dev Center Articles
    • Dev Center Changelog
    • Heroku
    • Heroku Status
  • Facebook
  • Instagram
  • Github
  • LinkedIn
  • YouTube
Heroku is acompany

 © Salesforce.com

  • heroku.com
  • Terms of Service
  • Privacy
  • Cookies
  • Cookie Preferences