Incompatible HttpClient Version

Oct 13, 2025 by wbrum.org 16 views

Introduction

When upgrading Apache HttpClient 5.x from version 5.3.1 to 5.4 in a Spring Boot application, users may encounter a 403 error when using the RestClient instance. This issue can be particularly frustrating, especially when the application was previously working without any issues. In this article, we will delve into the possible causes of this problem and provide a step-by-step guide to resolve the issue.

Background Information

Apache HttpClient 5.x is a popular and widely-used library for making HTTP requests in Java applications. It provides a flexible and customizable way to interact with web servers and APIs. Spring Boot, on the other hand, is a popular framework for building web applications in Java. It provides a lot of features out of the box, including support for Apache HttpClient 5.x.

Problem Description

When using the RestClient instance with a custom request factory backed by Apache HttpClient 5.x, users may encounter a 403 error after upgrading from version 5.3.1 to 5.4. This error can occur when making HTTP requests to a web server or API.

Possible Causes

There are several possible causes of this issue:

Incompatible HttpClient Version: The Apache HttpClient 5.x version may not be compatible with the Spring Boot version being used.
Custom Request Factory Configuration: The custom request factory may not be configured correctly, leading to issues with the HTTP requests.
Web Server or API Configuration: The web server or API being accessed may have changed its configuration, leading to issues with the HTTP requests.

Troubleshooting Steps

To resolve the issue, follow these troubleshooting steps:

Step 1: Verify Apache HttpClient Version

Verify that the Apache HttpClient 5.x version being used is compatible with the Spring Boot version. You can check the version by running the following command:

System.out.println(HttpClient.Version.valueOf("HTTP/1.1"));

This will print the version of the Apache HttpClient being used.

Step 2: Check Custom Request Factory Configuration

Check the custom request factory configuration to ensure that it is correct. You can do this by checking the RestClient.Builder instance and verifying that the request factory is being used correctly.

RestClient.Builder builder = RestClient.builder(new CustomRequestFactory());

Step 3: Verify Web Server or API Configuration

Verify that the web server or API being accessed has not changed its configuration. You can do this by checking the web server or API documentation to ensure that the HTTP requests are being made correctly.

Step 4: Update Apache HttpClient Version

If the issue persists, try updating the Apache HttpClient version to a newer version. You can do this by updating the pom.xml file in your Maven project or the build.gradle file in your Gradle project.

Step 5: Check for Incompatible Dependencies

Check for any incompatible dependencies that may be causing the issue. You can do this by checking the project dependencies and verifying that they are compatible with the Apache HttpClient version being used.

Step 6: Enable Debug Logging

Enable debug logging to get more information about the issue. You can do this by setting the logging.level.org.apache.http property to DEBUG.

logging.level.org.apache.http=DEBUG

Step 7: Check for Custom Request Factory Issues

Check for any issues with the custom request factory. You can do this by checking the CustomRequestFactory class and verifying that it is being used correctly.

Step 8: Verify Web Server or API Response

Verify that the web server or API is responding correctly. You can do this by checking the web server or API documentation to ensure that the HTTP requests are being made correctly.

Step 9: Check for Incompatible Spring Boot Version

Check for any incompatible Spring Boot version that may be causing the issue. You can do this by checking the Spring Boot version being used and verifying that it is compatible with the Apache HttpClient version.

Step 10: Update Spring Boot Version

If the issue persists, try updating the Spring Boot version to a newer version. You can do this by updating the pom.xml file in your Maven project or the build.gradle file in your Gradle project.

Conclusion

Resolving the RestClient 403 error after upgrading Apache HttpClient 5.x from version 5.3.1 to 5.4 in a Spring Boot application can be a challenging task. However, by following the troubleshooting steps outlined in this article, you should be able to resolve the issue and get your application working correctly again.

Additional Resources

For more information on Apache HttpClient 5.x and Spring Boot, refer to the following resources:

Example Use Cases

Here are some example use cases for the RestClient instance with a custom request factory backed by Apache HttpClient 5.x:

Making HTTP GET Requests: Use the RestClient instance to make HTTP GET requests to a web server or API.

RestClient client = RestClient.builder(new CustomRequestFactory()).build();
Response response = client.get("https://example.com/api/data");

Making HTTP POST Requests: Use the RestClient instance to make HTTP POST requests to a web server or API.

RestClient client = RestClient.builder(new CustomRequestFactory()).build();
Response response = client.post("https://example.com/api/data", new JSONObject());

Making HTTP PUT Requests: Use the RestClient instance to make HTTP PUT requests to a web server or API.

RestClient client = RestClient.builder(new CustomRequestFactory()).build();
Response response = client.put("https://example.com/api/data", new JSONObject());

Making HTTP DELETE Requests: Use the RestClient instance to make HTTP DELETE requests to a web server or API.

RestClient client = RestClient.builder(new CustomRequestFactory()).build();
Response response = client.delete("https://example.com/api/data");

Q: What is the cause of the RestClient 403 error after upgrading Apache HttpClient 5.x from version 5.3.1 to 5.4 in a Spring Boot application?

A: The cause of the RestClient 403 error after upgrading Apache HttpClient 5.x from version 5.3.1 to 5.4 in a Spring Boot application can be due to several reasons, including:

Incompatible HttpClient Version: The Apache HttpClient 5.x version may not be compatible with the Spring Boot version being used.
Custom Request Factory Configuration: The custom request factory may not be configured correctly, leading to issues with the HTTP requests.
Web Server or API Configuration: The web server or API being accessed may have changed its configuration, leading to issues with the HTTP requests.

Q: How can I verify the Apache HttpClient version being used in my Spring Boot application?

A: You can verify the Apache HttpClient version being used in your Spring Boot application by running the following command:

System.out.println(HttpClient.Version.valueOf("HTTP/1.1"));

This will print the version of the Apache HttpClient being used.

Q: What is the correct way to configure the custom request factory in my Spring Boot application?

A: The correct way to configure the custom request factory in your Spring Boot application is to use the RestClient.Builder instance and specify the custom request factory as follows:

RestClient.Builder builder = RestClient.builder(new CustomRequestFactory());

Q: How can I troubleshoot the issue with the custom request factory in my Spring Boot application?

A: To troubleshoot the issue with the custom request factory in your Spring Boot application, you can follow these steps:

Check the custom request factory configuration: Verify that the custom request factory is being used correctly.
Enable debug logging: Enable debug logging to get more information about the issue.
Check for custom request factory issues: Check for any issues with the custom request factory.

Q: What is the correct way to make HTTP requests using the RestClient instance with a custom request factory in my Spring Boot application?

A: The correct way to make HTTP requests using the RestClient instance with a custom request factory in your Spring Boot application is to use the RestClient instance and specify the HTTP method and URL as follows:

RestClient client = RestClient.builder(new CustomRequestFactory()).build();
Response response = client.get("https://example.com/api/data");

Q: How can I resolve the issue with the web server or API configuration in my Spring Boot application?

A: To resolve the issue with the web server or API configuration in your Spring Boot application, you can follow these steps:

Verify the web server or API configuration: Verify that the web server or API is configured correctly.
Check for web server or API changes: Check for any changes to the web server or API configuration.
Update the web server or API configuration: Update the web server or API configuration to resolve the issue.

Q: What is the correct way to update the Apache HttpClient version in my Spring Boot application?

A: The correct way to update the Apache HttpClient version in your Spring Boot application is to update the pom.xml file in your Maven project or the build.gradle file in your Gradle project.

Q: How can I resolve the issue with the incompatible Spring Boot version in my application?

A: To resolve the issue with the incompatible Spring Boot version in your application, you can follow these steps:

Verify the Spring Boot version: Verify that the Spring Boot version is compatible with the Apache HttpClient version.
Update the Spring Boot version: Update the Spring Boot version to a compatible version.
Update the Apache HttpClient version: Update the Apache HttpClient version to a compatible version.

Q: What are some best practices for using the RestClient instance with a custom request factory in my Spring Boot application?

A: Some best practices for using the RestClient instance with a custom request factory in your Spring Boot application include:

Use a custom request factory: Use a custom request factory to configure the HTTP requests.
Enable debug logging: Enable debug logging to get more information about the issue.
Verify the web server or API configuration: Verify that the web server or API is configured correctly.
Update the Apache HttpClient version: Update the Apache HttpClient version to a compatible version.
Update the Spring Boot version: Update the Spring Boot version to a compatible version.