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