The proposed NU7 change would disable version 4 transactions, leaving ZEC in Zcash’s legacy Sprout shielded pool unspendable.

Zcash users holding ZEC in the network’s legacy Sprout shielded pool should move it before the planned NU7 upgrade or risk losing the ability to spend it.

Under Zcash Improvement Proposal-2003, NU7 would stop accepting the older transaction format that allows users to spend Sprout funds. ZEC left in the pool would become unspendable after the upgrade.

The proposal would not burn Sprout funds and leaves open the possibility of restoring access later. However, it warns that holders may never be able to spend funds left in the pool.

A user posting as “vaspholdings” on the Zcash Community Forum urged ZEC holders on Sunday to check old wallets before the upgrade. Those wallets may contain Sprout ZEC, transparent ZEC or both, the user wrote. Only funds in the Sprout pool face the proposed restriction.

Zcash co-founder Zooko Wilcox also shared the warning on X.

NU7 is scheduled to activate on testnet Oct. 6. Zcash expects to decide on Oct. 20 whether to proceed with the targeted Nov. 5 mainnet activation.

The upgrade would also cut Zcash’s target block time from 75 seconds to 25 seconds. Its planned changes to issuance would preserve the network’s halving schedule.

ZEC traded at $1,627.82 at the time of writing, up 8% in the past 24 hours and almost 40% over the past week, according to CoinGecko.

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