According to ZEC official information, there will be a hard fork for ZEC at block height 347,500 (expected around 7:00 on June 26, 2018, GMT+8). To avoid failure to deposit and withdraw, ZEC official team recommends that deposit and withdrawal should be suspended at least one hour in advance.
To support ZEC's upgrade, Huobi Pro is expected to suspend ZEC deposit and withdrawal at 21:00 on June 25, 2018 (GMT+8). After the ZEC hard fork stabilizes, we will resume the service promptly and advise the specific time with another announcement. We apologize for the inconvenience caused during the suspension.
ZEC official announcement: https://z.cash/support/network-upgrade-guide.html
June 20, 2018