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When an application goes to Error or keeps restarting, the answer is almost always in its output. This guide shows where to look and how to read what you find.

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Where the logs are

  • Dashboard: the application’s Logs tab shows the live output, including the dependency installation and the build.
  • CLI: vertra logs -f follows the output from the terminal. See CLI.
  • API: Get Logs.
Always read from the first error line, not the last: the last line is usually a consequence.

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What the platform does when the app crashes

Auto-restart is always on. An exit with code 0 is treated as a normal stop and isn’t restarted; any other exit is. If the application crashes 5 times in 10 minutes, auto-restart is paused for 24 hours and the application stays stopped: fix the cause and start it by hand.

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Match the symptom

Exit code 0: the program simply finished. A server must keep listening and a bot must stay logged in. Check the entry point in Config points to the right file.
That’s an out-of-memory kill. Watch the memory graph on the Overview tab: if it climbs to the limit before each crash, raise the RAM in Config or reduce what the process holds in memory. Java, headless browsers and big caches need 512 MB or more.
The dependency isn’t declared. Node.js: it’s in devDependencies or missing from package.json. Python: missing from requirements.txt. The container only installs what the manifest lists.
INSTALL_TIMEOUT means dependency installation passed 15 minutes; BUILD_FAILED means your build command exited with an error (the build output is in the logs); BUILD_TIMEOUT means it passed 10 minutes.
The server listens on localhost or a fixed port. Listen on 0.0.0.0 and read PORT:
.env files aren’t read at runtime. Set the variable in Config and restart: a changed variable only reaches the process after a restart.
Compare runtime versions (set VERSION in Configuration), don’t upload node_modules/venv built on your machine, and remember file names are case-sensitive on Linux: ./Config.js and ./config.js are different files.

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Check before you deploy

vertra doctor inspects the current directory for the most common problems before anything is sent. The full list of error codes is in Common errors.