Troubleshooting TooManyRemoveHeadersInResponseHeadersPolicyException in AWS CloudFront

Introduction

AWS CloudFront is a popular content delivery network (CDN) service provided by Amazon Web Services (AWS). It accelerates content delivery by caching various static and dynamic assets, reducing latency, and improving user experience. CloudFront offers a range of features and configurations to control how content is served to end-users. However, there are instances when you might encounter an exception called “TooManyRemoveHeadersInResponseHeadersPolicyException.” In this article, we will delve into the details of this exception, explore its causes, and discuss some potential solutions.

Understanding the Exception

The TooManyRemoveHeadersInResponseHeadersPolicyException is raised when you attempt to create or update a CloudFront distribution, and the specified response headers policy attempts to remove too many headers. CloudFront allows removing a limited number of headers from the response before it throws this exception.

Causes of the Exception

1. Response Headers Limit: CloudFront has a predefined limit on the number of headers that can be removed in a response headers policy. If you exceed this limit, the exception will be thrown. By default, this limit is set to 10.

2. Incompatible Changes: The exception might occur if you try to create or update a CloudFront distribution with a response headers policy that includes headers not supported by CloudFront, such as Content-Security-Policy. CloudFront has a specific set of supported headers, and any unrecognized headers will not be allowed to be removed.

Possible Solutions

Solution 1: Review and Reduce Removed Headers

To tackle this exception, carefully review the response headers policy and identify headers that are not essential for your use case. Reduce the number of removed headers in the policy to ensure it falls within the acceptable limits. By minimizing the number of headers removed, you can avoid triggering the exception and successfully create or update your CloudFront distribution.

Here’s an example of a response headers policy that removes two headers:

ResponseHeaders headers = new ResponseHeaders()
            .withQuantity(2)
            .withItems("X-Frame-Options", "Strict-Transport-Security");

Solution 2: Check Header Compatibility

Make sure that the headers you are trying to remove in the policy are actually supported by CloudFront. Refer to the official documentation [^1^] to verify the list of supported headers. If the headers you want to remove are not supported, you can consider alternatives such as modifying the headers at the origin server or removing them using Lambda@Edge functions.

Solution 3: Raising the Limit (Advanced)

By default, CloudFront allows removing up to 10 headers in a response headers policy. If your use case requires removing more headers, you can request an increase in the limit from AWS Support. However, it’s always recommended to minimize the number of removed headers for optimal performance and compatibility.

Conclusion

The TooManyRemoveHeadersInResponseHeadersPolicyException can be encountered when creating or updating a CloudFront distribution if the response headers policy tries to remove too many headers. By carefully reviewing and reducing the number of removed headers, verifying header compatibility, and requesting a limit increase (if necessary), you can overcome this exception and successfully configure your CloudFront distribution.

Remember to refer to the official AWS CloudFront documentation [^2^] for detailed guidance and best practices related to response headers policies and configuration.

Happy CloudFront distribution deployment!

References