Caution is advised, however, regarding the term « freeze. » The ZEC will neither be destroyed nor burned. They will remain recorded on the blockchain, but could become technically unusable after the activation of NU7.
Zcash Wants to Close the Door on Sprout
The decision comes as Zcash experiences a new phase of interest in the crypto market. Yet Sprout represents a very old part of its architecture: it was Zcash’s first shielded transaction protocol, which was gradually replaced by Sapling and then Orchard.
According to ZIP 2003, Sprout currently introduces additional complexity and attack surface despite being very rarely used. The pool still contained fewer than 23,000 ZEC during the community consultations in August.
NU7 will make v4 transactions invalid. However, transfers from Sprout can only be carried out using this format. Therefore, ZEC left in the pool will no longer be spendable. The official document advises affected holders to move them « without delay. »
ZEC Will Not Be Burned
This distinction is important. ZIP 2003 specifies that these funds will remain issued. Disabling them does not constitute a burn or a reduction in the ZEC supply.
A future upgrade could theoretically restore v4 transactions or create another mechanism to recover the funds. However, there is no guarantee that such a solution will ever be adopted. Holders who do not migrate therefore run the risk of keeping ZEC that is visible in the blockchain history, but impossible to move.
Only Sprout funds are affected. Transparent ZEC in an old wallet will not automatically become unusable. The issue specifically targets legacy shielded notes held in this pool.
NU7 Also Accelerates Zcash
The removal of v4 transactions is only one part of NU7. The upgrade is also set to reduce the target block time from 75 to 25 seconds, while preserving the Zcash halving schedule.
The timeline remains subject to final technical validations: testnet activation planned for October 6, final decision and mainnet activation height expected on October 20, and a targeted launch on the mainnet on November 5, 2026.
For ordinary Zcash users, NU7 should therefore not cause a general freezing of wallets. The risk is much more targeted: funds left in a privacy technology that has become obsolete. This is also a concrete illustration of the difficulty of upgrading a decentralized crypto network without keeping all its legacy technical layers indefinitely.
For Sprout holders, the timeline is now much less theoretical. Once NU7 is activated, waiting could mean waiting for a future protocol modification that is currently in no way guaranteed.
