Header Limits: Headers (metadata) are constrained not only by Swarm but by all services, proxies, and clients (such as Elasticsearch, Twisted, Jetty, and HAProxy) handling objects. A Swarm object may have any number of annotations associated with it, but each annotation object is subject to these limits. The persisted metadata on Swarm objects must fall within these limits by default:
500 - The total number of headers on an object
32 KB - The combined length of all headers (key/value pairs); exceeding this returns a 400 (Bad Request) error
16 KB - The maximum length for a given header (key/value pair)