# Logs and crashes

> Where to read what your app prints, where the build log is, and what happens when an app keeps crashing.

There are two logs: the runtime log of the app, and the build log of each deployment.

## Runtime log

Open **Logs**. It shows the newest lines from every replica and refreshes every 3 seconds. You can pick one replica to read only its lines. The page calls a replica a machine.

What is in it:

- **What your app prints.** Everything written with `console.log` and `console.error`.
- **What the platform notes.** When a replica starts and stops, when it waits for your app to listen, when the app ran out of memory.

Print to the console. A log your app writes to a file is on the temporary disk of one replica, where you cannot read it.

## Build log

Open a deployment under **Deployments** to read its **Build log**: the install, your build commands and your deploy commands, with their output. It is kept for 90 days after the deployment ended.

## When the app crashes

- **It is started again.** A replica that exits with an error is restarted, up to 3 times.
- **It is noticed.** If the app keeps crashing and no replica is serving, the overview says so and the team gets a notification: "App keeps crashing".
- **The log says why.** The last lines before the exit are in the runtime log, with the exit code.

| Line in the runtime log | What to do |
| --- | --- |
| The app exited with code N | Read the lines above it: your app printed the error |
| The app ran out of memory and was stopped | Choose a larger size under [Scaling](https://arrangic.com/docs/scaling.md) |
| The start command could not be run | Check the start command in the [build settings](https://arrangic.com/docs/build-settings.md#start-command) |
| The app kept crashing: after N restarts it is not started again | Fix the error and deploy again |

[Troubleshooting](https://arrangic.com/docs/troubleshooting.md) has more messages.

## Numbers for the last day

**Overview** shows CPU and memory for each replica, and requests and response time across all replicas, for the last 24 hours.

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This page on the site: https://arrangic.com/docs/logs  
All pages of the documentation: https://arrangic.com/llms.txt