React + .Net core api issue
Hey everyone, I need some help with an issue I'm facing after deploying my React + ASP.NET Core Web API project on an AWS EC2 Windows Server (IIS).
Project Setup (Development)
• Frontend (React):
o Works fine locally on:
https://localhost:5173/
https://192.168.1.106:5173/ (Network)
• Backend (.NET Core API):
o Works fine locally on:
https://localhost:7269/
http://localhost:5031/
• API Configuration in React (config.js):
o const API_URL = 'https://localhost:7269/api'; (Used in Axios for API calls)
Deployment Process
1. Published the project (.server) to a folder containing both frontend and backend.
2. Set up AWS EC2 (Windows Server) with IIS:
o Installed IIS, .NET Hosting Bundle, SQL Server & SSMS.
o Opened ports 80, 443, 1433 (both in Windows Firewall and AWS Security Group).
o Created a site in IIS with port 80, pointing to the published folder.
o Database Connection String (Accessible):
"DefaultConnection": "Server=51.21.196.163,1433;Database=CelestialCharm;User Id=**;Password=***;TrustServerCertificate=True;"
3. Accessing the Website
o http://51.21.196.163:80 → React site loads successfully.
o API Login/Signup endpoints work, but other API calls return 500 errors.
Issues • API calls in the LoginController work, but all other API requests return 500 Internal Server Error. • The issue does not occur in development; only happens after deployment. What I’ve Tried • Checked that the backend is running on IIS. • Ensured database is accessible from the server. • Opened necessary firewall and security group ports. Questions • What could be causing API calls to fail with a 500 error only after deployment? • How can I debug this in IIS or ASP.NET Core logs? • Is there something I need to configure in IIS for proper API routing?
Issues • API calls in the LoginController work, but all other API requests return 500 Internal Server Error. • The issue does not occur in development; only happens after deployment. What I’ve Tried • Checked that the backend is running on IIS. • Ensured database is accessible from the server. • Opened necessary firewall and security group ports. Questions • What could be causing API calls to fail with a 500 error only after deployment? • How can I debug this in IIS or ASP.NET Core logs? • Is there something I need to configure in IIS for proper API routing?
11 Replies
@PixxelKick
...wat?
Can u help
We both have the same error
step 1 is pulling logs to figure out whats causing the 500 error
you should have some kind of logging on your backend since its aspnet, you should be able to inspect those logs and find out what errors are being thrown
How can i do that
that entirely depends on your logging backend
@Geeked will share code tmrrow maybe u could help
Can you see what the logging says? https://learn.microsoft.com/en-us/aspnet/core/host-and-deploy/iis/logging-and-diagnostics?view=aspnetcore-9.0#enhanced-diagnostic-logs
Hey @Lex Li,
We're experiencing a critical issue with our production API endpoint:
https://51.21.196.163/api/Home/getCompanyDescription.
- Problem:
The API is taking approximately 20-21 minutes to respond.
Detailed analysis from Postman indicates the vast majority of this delay is in the "Waiting (TTFB)" phase, meaning the server is taking an extremely long time to send the first byte of data.
All other request phases (DNS, TCP, SSL, Download, Process) are completing in milliseconds.
- Key Information:
The backend is a .NET Core application hosted on an EC2 IIS server.
The database is SQL Server, but we've ruled out the database itself as the primary cause, as it works quickly from my development environment.
The issue is isolated to the EC2 IIS server environment.
The Stored procedure that is being called takes 6 seconds to run.
- What We've Investigated:
We've focused on the .NET Core code for potential synchronous blocking operations.
We're checking IIS configurations for any anomalies.
We are checking the EC2 server resources with cloud watch.
- Request for Assistance:
Does anyone have experience with similar TTFB delays in .NET Core on IIS?
Any insights into potential IIS configuration issues or .NET Core code patterns that could cause this?
Any idea how to check for network issues that could add 20 minutes of latency only for this API call?
Any suggestions for further debugging steps on the EC2 server?
We need to resolve this ASAP as it's severely impacting our application's performance.
Thanks in advance for any help!
Just add logging at any critical points of logic where a delay might happen in the flow of logic, reproduce the problem, and then inspect the logs for where the sudden slowdown occurs
The database is SQL Server, but we've ruled out the database itself as the primary cause, as it works quickly from my development environment.Is it that exact same database that the "prod" app points at? Or is it a seperate "dev" DB you tested against? Its critical to be 100% sure you verify the behavior against the exact same database too Id recommend, as always, start with fixing your logging. 99% of debugging production issues is getting your logs to be sufficient to show where the issue happens. Only in the case where you are failing silently and logs arent even happening (because it fails before it even goes inside your C# code) is when you gotta be worried
The proper channel to request technical support (like from Microsoft Support) is to go through a site like https://support.microsoft.com and open a support case. If the symptom is "The API is taking approximately 20-21 minutes to respond", usually hang dump analysis can reveal the culprit in a couple of hours by an experienced professional. You can do the same if you know the tools/profilers and your codebase very well.
There might be other tips to improve web app performance and observability, but you can apply them once this urgent issue is resolved.