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)
			writeErrorResponse(ctx, w, errAPI, r.URL)
			return
		}

		// Make sure formValues adhere to policy restrictions.