Electrum wallet hacked, servers replaced with malicious versions. This, in particular, is reported by the user Reddit under the nickname Crypto God.
According to him, the hacker installed a bunch of malicious servers. If the Electrum wallet is connected to one of these servers, then the user sees an "official" error message when performing an outgoing transaction. It also speaks of the need to update the wallet and offers to follow a fraudulent link.
Crypto God also cites one of the attacker's BTC addresses, on which 243 Bitcoins have already been accumulated.
Another Reddit user has posted a post about the problem that is similar in content. Also, the problem is actively discussed on GitHub.
There is an ongoing phishing attack against Electrum users. Our official website is https://t.co/aHiZIZH54e Do not download Electrum from any other source. More on the attack here: https://t.co/x5mPVspKfO
— Electrum (@ElectrumWallet) December 27, 2018
Electrum representatives confirmed information about an ongoing phishing attack by providing the correct link to their official website.