Fixing script start.sh not found errors in Railway deployments

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Summary

A Railway deployment failed because the system reported “Script start.sh not found”, despite the user creating a start.sh file and configuring the command. This prevented the FastAPI application from starting correctly, halting deployment.

Root Cause

The primary issue was a missing or incorrect path specification for the start.sh script in Railway’s deployment configuration. Additional contributing factors:

  • The start.sh script was not in the expected working directory (typically the project root).
  • The script lacked executable permissions on the Railway OS (e.g., Unix-based systems require chmod +x start.sh).
  • The uRailway command in the app settings did not use an absolute path, causing relative path resolution to fail.

Why This Happens in Real Systems

  • Railway executes commands from the project root directory, not the local development environment. If start.sh is in a subfolder (e.g., backend/start.sh), the relative path ./start.sh fails.
  • GitHub repositories often use platform-specific configurations (e.g., Windows paths) that conflict with Railway’s Linux-based environment.
  • Deployments skip local file system assumptions, so hidden files (e.g., .sh) may not propagate correctly if .gitignore excludes them.

Real-World Impact

  • Deployment failures delay feature releases and critical fixes.
  • Frustration and wasted time as teams troubleshoot path issues instead of core logic.
  • Inconsistent staging/testing environments where “works locally” regressions occur.

Example or Code

The user’s start.sh might look like: 

#!/bin/bash  
uvicorn main:app --host 0.0.0.0 --port $PORT

However, if the file isn’t in the project root or lacks execute permissions, the deployment fails.

How Senior Engineers Fix It

  1. Verify Script Location:
    • Place start.sh in the project root and commit it to the repository.
    • Check .gitignore to ensure the file isn’t excluded.
  2. Set Executable Permissions: 
    chmod +x start.sh  # Run this locally before deployment
  3. Use Absolute Paths in Configuration:
    Update Railway’s “Start Command” field to use the full path: 

    ./start.sh  # Relative path (works if in project root)  
# OR  
/home/user/repo/start.sh  # Absolute path (replace with actual route)
  4. Test Locally:
    Run ./start.sh in the project root to confirm it works without errors.

Why Juniors Miss It

  • Overlooking Environment Differences: Assuming local OS/file system quirks apply to Railway.
  • Neglecting Permissions: Forgetting to make scripts executable (chmod +x).
  • Misunderstanding Deployment Workflow: Not realizing Railway runs commands from the project root.
  • Skipping Debugging Steps: Failing to test the script locally with the exact command Railway uses.

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