c2pool 0.2.12.6 fixes a share-chain bug that could cut the payout of an LTC or DASH block

The c2pool project released version 0.2.12.6 on 14 November 2026. It is a share-chain fix for Litecoin and Dash nodes. The project recommends the update for every LTC and DASH node, one node at a time. Bitcoin, DigiByte, Bitcoin Cash and BIP-110 nodes are unchanged. The details are in the c2pool 0.2.12.6 release notes.

What went wrong

When two shares are built on the same parent at almost the same time, p2pool gives the share that also solved a block one extra share of weight. That share then wins against an equal-work sibling, and even against a branch that is one share longer. c2pool did not do this: it picked between same-second siblings at random. A share that had found a block could therefore end up off the best share chain. The block itself stayed on the coin chain, so nothing was lost there, but the finder lost one share of payout weight, and dashboards disagreed about the block count.

What the fix changes

• A block-solving share now gets the same extra weight as in p2pool. If everything else is tied, the larger share hash wins, again as in p2pool.
• The extra weight is given only if the share's block target is the network's real target for its parent block, and that parent is within 6 blocks of the node's own chain tip. A share that claims an easier target than the network gets no extra weight.
• On LTC, only Litecoin block solutions count, as in p2pool. A share that solved only a Dogecoin block gets no extra weight. An LTC node running with --no-embedded-ltc on litecoind also gives no extra weight and behaves as before.

The update changes only which of the already valid shares a node builds on. Share validation, payouts and the network protocol are unchanged, and nodes on older versions stay on the same share chain.

What operators should do

Upgrade LTC and DASH nodes one at a time. The dashboard's "Blocks in Window" figure now also counts blocks whose share lost the head race, listed separately, so it matches the block chart. On DASH, share-version labels follow the live share version.

Two limits remain: --solo and --custodial are still disabled. On Linux, start the node through the package's start.sh or point the loader at the package lib/ folder: the binaries look for libsecp256k1.so.6, which most systems do not have. If you upgrade by copying only the binary, copy lib/ as well. The release notes include checksums signed with key 99556F8DE6AD66057A1A10EC50AB1379285EFE76.