it is not version related, and you don't need seed or private key or recovery or anything. this error simply means there has been some problem with your communication with the Electrum Node (the server) that you are connected to.
possible reasons? you have connectivity issues on your end. the server may have gone down or was not listening for incoming tx messages when you tried broadcasting.
solution? simply change server! it usually happens automatically when Electrum fails to communicate with the servers.
workaround? use the Preview window and instead of clicking "Broadcast" click on "Copy". this will copy your signed transaction to clipboard (you can paste it in a text file to see what it is). now go to any of these https://en.bitcoin.it/wiki/Transaction_broadcasting paste your transaction hex there and push it.