from reddit (
https://www.reddit.com/r/pivx/comments/77npm5/update_v303_has_been_developed_to_fix_a_chain/doo5e8d/ )
V3.0.4rc1 will be available in the morning.
Note; the wallet is for MN and staking purposes, it is not advised to send piv from these wallets until advised it is safe to do so.
A reindex of the blockchain will be required.
So it seems we have to wait for a bit longer. Until we are given a clear go-ahead, we should not use any version to make transactions.
And 3.0.3 won't be on the correct chain, I guess?