I received the very same error message so I wanted to know what's the new rule that got activated?
It's been there since i got into veil. I think it's something to do with them testing a fork on testnet.Weird I noticed that message for the first time after reading few posts here lol. BTW thanks for answering
The new rule was the deactivation of unlinkable zerocoin spends, so if you wish to stake anonymously you need to mint through RingCT currently.