writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)
			return
		}
	}

	// Handle policy if it is set.
	if len(policyBytes) > 0 {
		postPolicyForm, err := parsePostPolicyForm(bytes.NewReader(policyBytes))
		if err != nil {
			errAPI := errorCodes.ToAPIErr(ErrPostPolicyConditionInvalidFormat)
			errAPI.Description = fmt.Sprintf("%s '(%s)'", errAPI.Description, err)