HTTP 401 response code

The HTTP 401 response code indicates an "Unauthorized" error. This typically means that the request requires user authentication which has not been provided or which has failed. Here are some common reasons and solutions for this issue in a Spring Boot application:

1. Spring Security Configuration

If your Spring Boot application is using Spring Security, it might be configured to require authentication for accessing the API endpoints. This is a common scenario when Spring Security is included in the project dependencies.

Solutions:

• Provide Authentication Credentials: If your API requires authentication, you need to provide the correct credentials in your request header. In Postman, you can do this in the Authorization tab, selecting the type of authentication your API uses (like Basic Auth, Bearer Token, etc.) and entering the required credentials.
• Adjust Security Configuration: If the /users endpoint should be publicly accessible without authentication, you'll need to adjust your Spring Security configuration to permit requests to this endpoint. Here’s an example of how you might configure this in your WebSecurityConfigurerAdapter:

@Override
protected void configure(HttpSecurity http) throws Exception {
    http
        // ... other configurations ...
        .authorizeRequests()
        .antMatchers("/users").permitAll() // Permit requests to /users endpoint
        .anyRequest().authenticated()
        // ... other configurations ...
}

 

2. CSRF Protection

Spring Security's CSRF (Cross-Site Request Forgery) protection is enabled by default. If you are making a POST request to your Spring Boot application from Postman or another REST client, CSRF protection might block it.

Solutions:

• Include CSRF Token: If CSRF protection is necessary (usually for browser-based applications), include the CSRF token in your request.
• Disable CSRF Protection for API Endpoints: If you're building a stateless REST API (especially one used by non-browser clients), you might consider disabling CSRF protection for those endpoints:

@Override
protected void configure(HttpSecurity http) throws Exception {
    http
        // ... other configurations ...
        .csrf().disable() // Disable CSRF protection
        // ... other configurations ...
}

3. CORS Configuration

While the 401 error isn't directly related to CORS (Cross-Origin Resource Sharing), incorrect CORS settings can sometimes manifest as authentication issues, especially if you're calling the API from a different domain.

Solution:

• Configure CORS Settings: Ensure that your Spring Boot application has the correct CORS settings if your API is being accessed from a different domain.

4. Check Server Logs

Finally, check your server logs for any additional information or error messages related to the failed request. The logs can provide more specific details about why the request was unauthorized.

By addressing these areas, you should be able to resolve the 401 error and successfully make POST requests to your /users endpoint.