Heroku

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Heroku Error Codes

Last Updated: 15 February 2012

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Whenever your app experiences an error, Heroku will return a standard error page with the HTTP status code 503. To help you debug the underlying error, however, the platform will also add custom error information to your logs. Each type of error gets its own error code, with all HTTP errors starting with the letter H and all runtime errors starting with R.

H10 - App crashed

A crashed web process or a boot timeout on the web process will present this error.

2010-10-06T21:51:04-07:00 heroku[web.1]: State changed from down to starting
2010-10-06T21:51:07-07:00 app[web.1]: Starting process with command: `thin -p 22020 -e production -R /home/heroku_rack/heroku.ru start`
2010-10-06T21:51:09-07:00 app[web.1]: >> Using rails adapter
2010-10-06T21:51:09-07:00 app[web.1]: Missing the Rails 2.3.5 gem. Please `gem install -v=2.3.5 rails`, update your RAILS_GEM_VERSION setting in config/environment.rb for the Rails version you do have installed, or comment out RAILS_GEM_VERSION to use the latest version installed.
2010-10-06T21:51:10-07:00 heroku[web.1]: Process exited
2010-10-06T21:51:12-07:00 heroku[router]: Error H10 (App crashed) -> GET myapp.heroku.com/ web=web.1 queue=0 wait=0ms service=0ms bytes=0
2010-10-06T21:51:12-07:00 heroku[nginx]: GET / HTTP/1.1 | 75.36.147.245 | 8132 | http | 503

H11 - Backlog too deep

You can read about the Backlog Too Deep error in more depth in the article devoted to it.

There are too many HTTP requests in your backlog. Increasing your dynos is the usual solution.

2010-10-06T21:51:07-07:00 heroku[router]: Error H11 (Backlog too deep) -> GET myapp.heroku.com/ web=web.1 queue=51 wait=0ms service=0ms bytes=0
2010-10-06T21:51:07-07:00 heroku[nginx]: GET / HTTP/1.1 | 75.36.147.245 | 8132 | http | 503

H12 - Request timeout

For more information on request timeouts (including recommendations for resolving them), take a look at our article on the topic.

An HTTP request took longer than 30 seconds to complete. In the example below, the Rails app takes 37 seconds to render the page; the HTTP router returns a 503 prior to Rails completing its request cycle, but the Rails process continues and the completion message shows after the router message.

2010-10-06T21:51:07-07:00 app[web.2]: Processing PostController#list (for 75.36.147.245 at 2010-10-06 21:51:07) [GET]
2010-10-06T21:51:08-07:00 app[web.2]: Rendering template within layouts/application
2010-10-06T21:51:19-07:00 app[web.2]: Rendering post/list
2010-10-06T21:51:37-07:00 heroku[router]: Error H12 (Request timeout) -> GET myapp.heroku.com/ web=web.2 queue=0 wait=0ms service=0ms bytes=0
2010-10-06T21:51:37-07:00 heroku[nginx]: GET / HTTP/1.1 | 75.36.147.245 | 8132 | http | 503
2010-10-06T21:51:42-07:00 app[web.2]: Completed in 37400ms (View: 27, DB: 21) | 200 OK [http://myapp.heroku.com/]

H13 - Connection closed without response

This is an edge case that appears far more rarely than the other errors. There are certain malfunctioning binary gems and other cases where your web process accepts the connection, but then closes the socket without writing anything to it.

2010-10-06T21:51:37-07:00 heroku[router]: Error H13 (Connection closed without response) -> GET myapp.heroku.com/ web=web.2 queue=0 wait=0ms service=173ms bytes=0
2010-10-06T21:51:37-07:00 heroku[nginx]: GET / HTTP/1.1 | 75.36.147.245 | 8132 | http | 503

H14 - No web processes running

This is most likely the result of scaling your web processes down to zero through the client.

$ heroku scale web=0

Use the heroku ps command to determine the state of your web processes.

H15 - Idle connection

The idle connection error is logged when a request is terminated due to 55 seconds of inactivity.

H16 - Redirect to herokuapp.com

Apps on Cedar’s new HTTP routing stack use the herokuapp.com domain. Requests made to a Cedar app at its deprecated heroku.com domain will be redirected to the correct herokuapp.com address and this redirect message will be inserted into the app’s logs.

H17 - Poorly formatted HTTP response

This error message is logged when the routing mesh detects a malformed HTTP response coming from a dyno.

H80 - Maintenance mode

This is not an error, but we give it a code for the sake of completeness. Note the log formatting is the same but without the word “Error”.

2010-10-06T21:51:07-07:00 heroku[router]: H80 (Maintenance mode) -> GET myapp.heroku.com/ web=none queue=0 wait=0ms service=0ms bytes=0
2010-10-06T21:51:07-07:00 heroku[nginx]: GET / HTTP/1.1 | 75.36.147.245 | 8132 | http | 503

H99 - Platform error

H99 is the only error that is caused by the Heroku platform.

This indicates an internal error in the Heroku platform. Unlike all of the other errors which will require action from you to correct, this one does not require action from you. Try again in a minute, or check the status site.

2010-10-06T21:51:07-07:00 heroku[router]: Error H99 (Platform error) -> GET myapp.heroku.com/ web=none queue=0 wait=0ms service=0ms bytes=0
2010-10-06T21:51:07-07:00 heroku[nginx]: GET / HTTP/1.1 | 75.36.147.245 | 8132 | http | 503

R10 - Boot timeout

A web process took longer than 60 seconds to bind to its assigned $PORT. This error is often caused by a process being unable to reach an external resource, such as a database.

2011-05-03T17:31:38+00:00 heroku[web.1]: State changed from created to starting
2011-05-03T17:31:40+00:00 heroku[web.1]: Starting process with command: `thin -p 22020 -e production -R /home/heroku_rack/heroku.ru start`
2011-05-03T17:32:40+00:00 heroku[web.1]: Error R10 (Boot timeout) -> Web process failed to bind to $PORT within 60 seconds of launch
2011-05-03T17:32:40+00:00 heroku[web.1]: Stopping process with SIGKILL
2011-05-03T17:32:40+00:00 heroku[web.1]: Process exited
2011-05-03T17:32:41+00:00 heroku[web.1]: State changed from starting to crashed

R11 - Bad bind

A process performed an incorrect TCP socket bind. This error is often caused by binding to a port other than the assigned $PORT. It can also be caused by binding to an interface other than 0.0.0.0 or *.

2011-05-03T17:38:16+00:00 heroku[web.1]: Starting process with command: `bundle exec ruby web.rb -e production`
2011-05-03T17:38:18+00:00 app[web.1]: == Sinatra/1.2.3 has taken the stage on 4567 for production with backup from Thin
2011-05-03T17:38:18+00:00 app[web.1]: >> Thin web server
2011-05-03T17:38:18+00:00 app[web.1]: >> Maximum connections set to 1024
2011-05-03T17:38:18+00:00 app[web.1]: >> Listening on 0.0.0.0:4567, CTRL+C to stop
2011-05-03T17:38:18+00:00 heroku[web.1]: Error R11 (Bad bind) -> Process bound to port 4567, should be 43411 (see environment variable PORT)
2011-05-03T17:38:18+00:00 heroku[web.1]: Stopping process with SIGKILL
2011-05-03T17:38:18+00:00 heroku[web.1]: Process exited
2011-05-03T17:38:20+00:00 heroku[web.1]: State changed from starting to crashed

R12 - Exit timeout

A process failed to exit within 10 seconds of being sent a SIGTERM indicating that it should stop. The process is sent SIGKILL to force an exit.

2011-05-03T17:40:10+00:00 app[worker.1]: Working
2011-05-03T17:40:11+00:00 heroku[worker.1]: Stopping process with SIGTERM
2011-05-03T17:40:11+00:00 app[worker.1]: Ignoring SIGTERM
2011-05-03T17:40:14+00:00 app[worker.1]: Working
2011-05-03T17:40:18+00:00 app[worker.1]: Working
2011-05-03T17:40:21+00:00 heroku[worker.1]: Error R12 (Exit timeout) -> Process failed to exit within 10 seconds of SIGTERM
2011-05-03T17:40:21+00:00 heroku[worker.1]: Stopping process with SIGKILL
2011-05-03T17:40:21+00:00 heroku[worker.1]: Process exited

R13 - Attach error

A process started with heroku run failed to attach to the invoking client.

2011-06-29T02:13:29+00:00 app[run.3]: Awaiting client
2011-06-29T02:13:30+00:00 heroku[run.3]: State changed from starting to up
2011-06-29T02:13:59+00:00 app[run.3]: Error R13 (Attach error) -> Failed to attach to process
2011-06-29T02:13:59+00:00 heroku[run.3]: Process exited

R14 - Memory quota exceeded

A process requires memory in excess of its 512MB quota. If this error occurs, the process will page to swap space to continue running, which may cause degraded process performance.

2011-05-03T17:40:10+00:00 app[worker.1]: Working
2011-05-03T17:40:10+00:00 heroku[worker.1]: Process running mem=528MB(103.3%)
2011-05-03T17:40:11+00:00 heroku[worker.1]: Error R14 (Memory quota exceeded)
2011-05-03T17:41:52+00:00 app[worker.1]: Working

R15 - Memory quota vastly exceeded

A processes requires vastly more memory than its 512MB quota and is consuming excessive swap space. If this error occurs, the process will be killed by the platform.

2011-05-03T17:40:10+00:00 app[worker.1]: Working
2011-05-03T17:40:10+00:00 heroku[worker.1]: Process running mem=2565MB(501.0%)
2011-05-03T17:40:11+00:00 heroku[worker.1]: Error R15 (Memory quota vastly exceeded)
2011-05-03T17:40:11+00:00 heroku[worker.1]: Stopping process with SIGKILL
2011-05-03T17:40:12+00:00 heroku[worker.1]: Process exited