Use the akamai-x-get-cache-tags pragma header to detect validation errors.

With cache tag purging, the Edge-Cache-Tag header is sent as a forward request response . When the forward response is received, the header is validated. If a validation error is detected, the header is re-written to remove all the problematic tags. In this case, the error is returned in a new X-Akamai-Cache-Tag-Error header, which is added to the response. If the header isn’t there, then the tags are valid.