Feathercoin 0.13.0.0 has been released. It is a mandatory update for anyone on a version prior to 0.9.6.2 as on block 2,120,000 it will start minting Version Bit blocks which will be rejected by old version of Feathercoin. Please make sure you have updated to 0.13 before block 2,120,000 which will be minted roughly in 17 days on the 8th March.
v0.8.7.4 should be compatible as it doesn't reject blocks with nVersion > 2. Well, until the new features like SegWit get activated.