The submitheader RPC decodes the given hexdata as a header and submits it as a candidate chain tip if valid.
submitheader "hexdata"
*bitcoin-cli help submitheader
submitheader "hexdata" Decode the given hexdata as a header and submit it as a candidate chain tip if valid. Throws when the header is invalid. Arguments: 1. hexdata (string, required) the hex-encoded block header data Result: null (json null) None Examples: > bitcoin-cli submitheader "aabbcc" > curl --user myusername --data-binary '{"jsonrpc": "1.0", "id": "curltest", "method": "submitheader", "params": ["aabbcc"]}' -H 'content-type: text/plain;' http://127.0.0.1:8332/