I know that the Bitcoin Network would send an alert message which follows:
int32_t nID
The alert identification number – this allows nodes to identify double-messages.
int64_t nExpiration
The alert-expiry time.
int64_t nRelayUntil
Instructs nodes to cease rebroadcasting of the message.
int32_t nMinVer —> int32_t nMaxVer
The range of bitcoin protocol versions that this alert applies to.
std::setstd::string setSubVer
The current client software update that this alert message applies to.
int32_t nPriority
The priority of the alert message - however, this function has been rarely used.
However, this was later abandoned in 2016 where the public and private keys of the message were released to the public.
Does the Bitcoin Network still have a way of notifying nodes of a potential fatal bug/error? If not, what is done if the Bitcoin Network is compromised?