Mining pools

1- Your mining daemon (the one that creates new PoW blocks and announces them to the network) must be at v1.2.1.0 (not even v1.2.0.0 which will be disconnected by all PoSV wallets). Otherwise your new blocks won't be accepted by the network.
2- Your payout daemon (the one that creates transactions to pay miners shares of block rewards) should be upgraded to v1.3.0.0 because transactions created by pre-PoSV wallets will be ignored and discarded by PoSV wallets once PoSV kicks in at block 260800.