🧩 Issue: FastAPI Deployment Fails with ModuleNotFoundError: No module named 'jose'

📌 Context

I’m deploying a FastAPI backend (Python 3.12) on Railway using a split architecture:

• API service → requirements.txt
• Worker service → requirements-worker.txt
• Procfile:

web: uvicorn backend.main:app --host 0.0.0.0 --port $PORT  

The app works locally without issues, but fails after deployment.

🚨 Error Observed

From Railway logs:

ModuleNotFoundError: No module named 'jose'

👉

Stack trace shows failure during import:

from backend.app.core.jwt import create_access_token, decode_token
from jose import jwt, JWTError

📦 Dependencies (Relevant Section)

requirements.txt includes:

fastapi==0.115.0
uvicorn[standard]==0.30.0
pydantic[email]==2.6.1

sqlalchemy==2.0.25
psycopg2-binary==2.9.9
asyncpg==0.29.0

python-jose[cryptography]==3.3.0  ← INCLUDED
passlib[bcrypt]==1.7.4
argon2-cffi==23.1.0

So the missing module should be installed.

🔍 What I Already Verified

• App imports successfully locally
• python-jose[cryptography] is present in requirements.txt
• No duplicate or conflicting dependency entries
• No lazy import issues (JWT is required at startup)
• Worker-related dependencies separated correctly
• API does NOT import Celery / Redis at startup

🧪 Observed Behavior

• Railway deploy succeeds
• Container starts
• Immediately crashes on startup due to missing jose
• Logs repeatedly show same import failure loop

🤔 Suspected Cause

This looks like a build cache issue, where:

• Railway is not reinstalling dependencies
• Cached layer is reused
• python-jose never gets installed in runtime environment

❓ Questions

1. Does Railway sometimes skip dependency installation due to caching, even when requirements.txt changes?
2. What is the recommended way to force a clean rebuild?
3. Is there a known issue with:
   • Python 3.12 + Nixpacks
   • Optional dependency syntax like python-jose[cryptography]?
4. Should I:
   • Clear build cache manually?
   • Delete & recreate the service?
   • Use a custom build command?

🧯 Temporary Workarounds Tried

• Added new lines to requirements.txt to force rebuild
• Re-deployed multiple times
• Verified Procfile and entrypoint

Still facing the same issue.

Expected Behavior

App should start successfully and expose:

/docs (Swagger UI)
/openapi.json

🙏 Help Needed

Looking for guidance on:

• Forcing dependency reinstall on Railway
• Diagnosing build cache issues
• Any known compatibility issues with python-jose