[Next.js] Error: connect ECONNREFUSED or process.processTicksAndRejections

1. Countermeasures

Issue: Not localhost

# Frontend server with Next.js
next dev

# Backend server with FastAPI and uvicorn
uvicorn app:app --reload

Solution: Explicitly specify IP address.

# Frontend server with Next.js
next dev -H 192.168.11.2

# Backend server with FastAPI and uvicorn
uvicorn app:app --reload --host 192.168.11.2

It's necessary to explicitly specify the IP address for both.

2. Background

1. Trying to check the screen from a smartphone by connecting to the development server 192.168.11.2
2. The images stored on the backend server are not displayed
3. Change the URL of the backend server accessed by the Next.js frontend server from localhost to 192.168.11.2
4. An error occurs with fetch

3. Cause

Not very clear.

4. Related

• 【Next.js】getServerSideProps内で API実行するとError: connect ECONNREFUSEDになる - Zenn