Error on uploading to S3. It seems like something has been expired but which one?

Please note that for uploading an object using POST operation, you can setup a 'POST policy' for making authenticated requests that specifies conditions to validate the request. For example, the request must meet "expiration" which specifies the expiration date and time of the POST policy. If you upload an object using POST operation and the POST policy, the POST policy's expiration time will be checked against the client time. If the client time earlier than the expiration time, then you get the policy expired error. To resolve the issue, try changing the "expiration" time in the policy to current or future time. According to AWS POST policy, the upload must happen before the expiration time. Please check the link below for details. https://docs.aws.amazon.com/AmazonS3/latest/API/sigv4-HTTPPOSTConstructPolicy.html Request you to check the expiration time in the POST policy in your client and modify it to future time, before performing post operation. Please note that AWS support does not have insights to client side settings such as POST policy.