Why doesn't Amazon CloudFront cache files in the amount of time I specified?

Resolution

Be sure that the directives that you set on the Cache-Control or Expires headers don't conflict with each other. As a best practice, use the Cache-Control max-age directive instead of the Expires header. If you specify values for both, then CloudFront uses only the value that you set for Cache-Control max-age.

Additionally, verify that the Minimum TTL, Default TTL, and Maximum TTL that you set on the CloudFront distribution don't conflict with the Cache-Control or Expires headers.

If these cache-duration settings conflict with each other, then CloudFront might not cache objects for the set time, or CloudFront may not cache at all. Avoid these examples of cache-duration settings that conflict with each other:

• If you set the Maximum TTL to 5 minutes (300 seconds) and the Cache-Control max-age header to 1 hour (3600 seconds), then CloudFront caches the object for 5 minutes instead of 1 hour.
• If you set the Cache-Control max-age header to 3 hours and the Expires header to 1 month, then CloudFront caches the object for 3 hours instead of 1 month.
• If you set the Default, Minimum, and Maximum TTL to 0 seconds, then CloudFront always verifies that it has the most recent content from the origin.

Important: If you update an origin asset with a caching header, then CloudFront reflects the change only after CloudFront makes a new request to your origin. CloudFront makes a new request to your origin when the cached asset expires in the edge locations. Then, your distribution receives a new request for the asset. To force CloudFront to reflect the update before the cached asset is set to expire, invalidate the cache.

Related information

Object caching