Less than 10,000 blocks remain until block height 8,000,000 on Neo Legacy, at which point an upgrade to cease GAS generation on the network will take effect. NEO token holders that wish to keep receiving GAS rewards will need to migrate to Neo N3 to do so.

The scheduled update requires Neo-CLI v2.13.0 or later—nodes running earlier software versions that sync past the 8 millionth block will lose consistency with the rest of the network and will need to resynchronize from genesis. To avoid this, nodes should update before the milestone, expected to occur sometime on or around September 19th.

Although NEO wallets will not continue to receive GAS rewards on Neo Legacy, unclaimed GAS remains unchanged and can be claimed at any time until the network eventually stops in the far future.

The latest Neo-CLI node version can be downloaded from the following link:
https://github.com/neo-project/neo-node/releases/tag/v2.13.0