Zcash NU7 Upgrade Activated, Leaving $15 Million in Sprout Funds Locked

This upgrade went live at block number 3,543,405 precisely at 02:34 UTC, according to the blockchain analytics site ZecStats. At that time, approximately 12,224 ZEC remained in the Sprout shielded pool.

One key change introduced by NU7 is the reduction of the target block interval from 75 seconds down to 25 seconds. However, actual times between blocks will vary and gradually adjust to the new target as mining difficulty updates.

Following Zcash Improvement Proposal 2003, the NU7 upgrade rejects version 4 transactions, which are the only type that allows spending funds from the Sprout pool. Consequently, the locked ZEC can no longer be moved, although these coins have not been destroyed.

The protocol notes that future upgrades might restore access to these Sprout funds, either by re-enabling version 4 transactions or through other means. Nonetheless, developers caution that spending Sprout funds may never become possible again.

NU7 also implements a Network Sustainability Mechanism that removes 60% of transaction fees from circulation, planning to redistribute them later as mining rewards starting around February 2031.

Additionally, the upgrade keeps Zcash’s maximum supply fixed at 21 million ZEC and maintains the halving schedule, while applying restrictions on shielded activity aimed at lessening the synchronization load on wallet software.

why: This upgrade has significant ramifications by effectively locking millions of dollars in Sprout funds, changing transaction rules, and implementing mechanisms designed to sustain the network long term.