ots --bitcoin-node http://xxx:xxx@127.0.0.1:8332 stamp --btc-wallet some_file
Sent timestamp tx
Waiting for timestamp tx ... to confirm...
Waiting for timestamp tx ... to confirm...
Waiting for timestamp tx ... to confirm...
Confirmed by block ...
Submitting to remote calendar https://a.pool.opentimestamps.org
Submitting to remote calendar https://b.pool.opentimestamps.org
Submitting to remote calendar https://a.pool.eternitywall.com
Submitting to remote calendar https://ots.btc.catallaxy.com
Failed to create timestamp: need at least 2 attestations but received 0 within timeout
