Code Examples
Here are examples of how to test HTTP 412 responses in different programming languages:
Select options below to see how to use advanced features in your code:
Request:
curl https://free.mockerapi.com/412
Response Body:
{
"success": false,
"status": 412,
"statusText": "Precondition Failed - The client has indicated preconditions that the server does not meet",
"timestamp": "2025-10-08T10:30:45.123Z",
"request": {
"method": "GET",
"url": "/412",
"fullUrl": "https://free.mockerapi.com/412"
}
}Request:
fetch('https://free.mockerapi.com/412')
.then(response => {
console.log('Status:', response.status); // 412
return response.json();
})
.then(data => {
console.log('Response:', data);
})
.catch(error => {
console.error('Error:', error);
});Response Body:
{
"success": false,
"status": 412,
"statusText": "Precondition Failed - The client has indicated preconditions that the server does not meet",
"timestamp": "2025-10-08T10:30:45.123Z",
"request": {
"method": "GET",
"url": "/412",
"fullUrl": "https://free.mockerapi.com/412"
}
}Request:
import requests
response = requests.get('https://free.mockerapi.com/412')
print(f'Status Code: {response.status_code}') # 412
print(f'Response: {response.json()}')Response Body:
{
"success": false,
"status": 412,
"statusText": "Precondition Failed - The client has indicated preconditions that the server does not meet",
"timestamp": "2025-10-08T10:30:45.123Z",
"request": {
"method": "GET",
"url": "/412",
"fullUrl": "https://free.mockerapi.com/412"
}
}Request:
Response Body:
{
"success": false,
"status": 412,
"statusText": "Precondition Failed - The client has indicated preconditions that the server does not meet",
"timestamp": "2025-10-08T10:30:45.123Z",
"request": {
"method": "GET",
"url": "/412",
"fullUrl": "https://free.mockerapi.com/412"
}
}Request:
require 'net/http'
require 'json'
uri = URI('https://free.mockerapi.com/412')
response = Net::HTTP.get_response(uri)
puts "Status Code: #{response.code}" # 412
puts "Response: #{JSON.parse(response.body)}"Response Body:
{
"success": false,
"status": 412,
"statusText": "Precondition Failed - The client has indicated preconditions that the server does not meet",
"timestamp": "2025-10-08T10:30:45.123Z",
"request": {
"method": "GET",
"url": "/412",
"fullUrl": "https://free.mockerapi.com/412"
}
}Request:
package main
import (
"fmt"
"io"
"net/http"
)
func main() {
resp, err := http.Get("https://free.mockerapi.com/412")
if err != nil {
panic(err)
}
defer resp.Body.Close()
fmt.Printf("Status Code: %d\n", resp.StatusCode) // 412
body, err := io.ReadAll(resp.Body)
if err != nil {
panic(err)
}
fmt.Printf("Response: %s\n", body)
}Response Body:
{
"success": false,
"status": 412,
"statusText": "Precondition Failed - The client has indicated preconditions that the server does not meet",
"timestamp": "2025-10-08T10:30:45.123Z",
"request": {
"method": "GET",
"url": "/412",
"fullUrl": "https://free.mockerapi.com/412"
}
}Request:
import java.net.http.*;
import java.net.URI;
public class HttpStatusTest {
public static void main(String[] args) throws Exception {
HttpClient client = HttpClient.newHttpClient();
HttpRequest request = HttpRequest.newBuilder()
.uri(URI.create("https://free.mockerapi.com/412"))
.GET()
.build();
HttpResponse response = client.send(request,
HttpResponse.BodyHandlers.ofString());
System.out.println("Status Code: " + response.statusCode()); // 412
System.out.println("Response: " + response.body());
}
} Response Body:
{
"success": false,
"status": 412,
"statusText": "Precondition Failed - The client has indicated preconditions that the server does not meet",
"timestamp": "2025-10-08T10:30:45.123Z",
"request": {
"method": "GET",
"url": "/412",
"fullUrl": "https://free.mockerapi.com/412"
}
}Request:
const https = require('https');
https.get('https://free.mockerapi.com/412', (res) => {
console.log('Status Code:', res.statusCode); // 412
let data = '';
res.on('data', (chunk) => {
data += chunk;
});
res.on('end', () => {
console.log('Response:', JSON.parse(data));
});
}).on('error', (err) => {
console.error('Error:', err.message);
});Response Body:
{
"success": false,
"status": 412,
"statusText": "Precondition Failed - The client has indicated preconditions that the server does not meet",
"timestamp": "2025-10-08T10:30:45.123Z",
"request": {
"method": "GET",
"url": "/412",
"fullUrl": "https://free.mockerapi.com/412"
}
}What is HTTP 412 Precondition Failed?
HTTP 412 Precondition Failed indicates that the server cannot or will not process the request due to something that is perceived to be a client error. This could be malformed request syntax, invalid request message framing, or deceptive request routing.
The client should not repeat the request without modifications.
When Does This Happen?
A 412 Precondition Failed response is returned when:
- The request has invalid syntax or malformed request parameters
- Required parameters are missing from the request
- The request body contains invalid JSON or XML
- Query parameters have invalid values or formats
- The request URL is malformed or contains invalid characters
- Request headers contain invalid or conflicting values
Try It Live
Click the button below to make a live request and see the 412 Precondition Failed response
Common Use Cases
🔍 Input Validation Testing
Test how your application handles invalid input data and displays appropriate error messages to users.
🛡️ Error Handling
Ensure your application properly catches and handles bad request errors without crashing.
📝 Form Validation
Test form validation logic and ensure users receive clear feedback about invalid submissions.
🔄 API Testing
Verify that your API correctly validates request parameters and returns appropriate error responses.
🎨 UI/UX Development
Design and test error states in your user interface for invalid requests.
📚 Documentation
Provide examples of bad request scenarios in API documentation for developers.