Network Error
Network Error
Meaning
A Network Error occurs when a device, application, browser, or server is unable to establish or maintain communication over a network. It indicates that a request sent from a client could not successfully reach the destination server, or the server’s response could not be returned to the client.
Network errors can occur due to issues with internet connectivity, DNS resolution, firewalls, proxies, VPNs, server outages, routing problems, or network configuration.
Common Causes
1. No Internet Connection
- Wi-Fi disconnected
- Ethernet cable unplugged
- Mobile data disabled
2. DNS Resolution Failure
The domain name cannot be translated into an IP address.
Example:
- DNS server unavailable
- Incorrect DNS settings
- Domain does not exist
3. Server Down
The destination server is:
- Offline
- Under maintenance
- Crashed
- Restarting
4. Firewall Blocking
A firewall may block:
- Incoming requests
- Outgoing requests
- Specific ports
- Applications
5. Proxy Configuration Issues
Problems such as:
- Invalid proxy settings
- Authentication failure
- Proxy timeout
6. VPN Problems
VPN may:
- Disconnect unexpectedly
- Route traffic incorrectly
- Block specific services
7. Network Timeout
The server did not respond within the expected time.
Possible reasons:
- Slow internet
- High server load
- Large requests
- Congested network
8. SSL/TLS Certificate Problems
Examples:
- Expired certificate
- Invalid certificate
- Self-signed certificate
- Certificate mismatch
9. Incorrect URL
Examples:
- Wrong domain
- Typographical errors
- Invalid endpoint
10. Router or Modem Issues
- Router rebooting
- ISP outage
- Firmware issues
- DHCP problems
11. Port Blocking
Required ports may be blocked.
Examples:
- 80
- 443
- 22
- 3306
- 5432
12. CORS Restrictions
In web applications:
The browser blocks requests because the server does not allow cross-origin requests.
13. Rate Limiting
The server rejects requests due to:
- Too many requests
- API quota exceeded
- DDoS protection
14. Authentication Failure
Examples:
- Invalid API key
- Expired token
- Unauthorized request
15. ISP Outage
The Internet Service Provider is experiencing issues.
How to Fix
Step 1: Check Internet Connection
- Open another website.
- Restart Wi-Fi.
- Test using another network.
Step 2: Verify the URL
Ensure:
- Correct spelling
- Correct protocol (HTTP/HTTPS)
- Correct port
Step 3: Check Server Status
Verify that the server is online using:
- Hosting dashboard
- Server monitoring tools
- Ping tests
- Uptime monitoring services
Step 4: Flush DNS Cache
Windows
bash
ipconfig /flushdns
macOS
bash
sudo dscacheutil -flushcache
Linux
bash
sudo systemctl restart systemd-resolved
Step 5: Change DNS Server
Use:
- Google DNS
- 8.8.8.8
- 8.8.4.4
- Cloudflare DNS
- 1.1.1.1
- 1.0.0.1
Step 6: Disable VPN or Proxy
Temporarily disable:
- VPN
- Proxy
- Corporate network
Test again.
Step 7: Check Firewall Rules
Allow:
- Browser
- Application
- Required ports
Step 8: Verify SSL Certificate
Check:
- Expiry date
- Domain match
- Certificate chain
- Browser trust
Step 9: Restart Network Equipment
Restart:
- Router
- Modem
- Switch
- Computer
Step 10: Test Using Command-Line Tools
Ping
bash
ping google.com
Traceroute
Windows
bash
tracert google.com
Linux/macOS
bash
traceroute google.com
nslookup
bash
nslookup example.com
curl
bash
curl https://example.com
Step 11: Check Browser Console
Open:
Developer Tools → Network Tab
Look for:
- 404
- 500
- CORS
- Timeout
- SSL
- DNS errors
Step 12: Review Application Logs
Examples:
- Apache logs
- Nginx logs
- IIS logs
- Application logs
- CloudWatch
- Azure Monitor
Examples
Example 1
Error
Network Error
Reason
Internet connection lost.
Solution
Reconnect to the network.
Example 2
Error
ERR_CONNECTION_TIMED_OUT
Reason
Server took too long to respond.
Solution
Check server load, firewall settings, and internet connectivity.
Example 3
Error
ERR_NAME_NOT_RESOLVED
Reason
DNS lookup failed.
Solution
Verify the domain name and DNS configuration.
Example 4
Error
ECONNREFUSED
Reason
The destination server is not accepting connections on the requested port.
Solution
Ensure the service is running and the correct port is open.
Example 5
Error
ECONNRESET
Reason
The connection was unexpectedly closed by the remote server.
Solution
Check server logs, network stability, and firewall settings.
Example 6
Error
ETIMEDOUT
Reason
The request exceeded the configured timeout period.
Solution
Increase the timeout, optimize the request, or resolve network latency issues.
Example 7
Error
AxiosError: Network Error
Reason
The Axios HTTP client could not complete the request due to connectivity, CORS, SSL, or server issues.
Solution
Inspect the browser’s Network tab, verify the API endpoint, check CORS configuration, and ensure the server is reachable.
Example 8
Error
Fetch failed
Reason
The browser’s Fetch API could not retrieve the requested resource.
Solution
Confirm the URL, verify internet access, and check for CORS or SSL-related problems.
Example 9
Error
SocketException: Failed host lookup
Platform
Flutter / Dart
Reason
The hostname could not be resolved by DNS.
Solution
Verify the hostname, internet connection, and DNS settings.
Example 10
Error
java.net.UnknownHostException
Platform
Java
Reason
The application could not resolve the server’s hostname.
Solution
Check DNS resolution, network connectivity, and ensure the hostname is correct.