Bitcoin Core 31 changes how nodes organise pending transactions

Bitcoin Core 31.0 was released on 19 April with a redesigned mempool, the node’s collection of unconfirmed transactions. The release notes describe a cluster-based system for deciding which transactions to relay, replace, evict or include in block templates. Connected transactions are considered together, replacing earlier ancestor and descendant limits with cluster limits. The defaults allow up to 64 transactions and 101 kilobytes of virtual size per cluster. Bitcoin release notes.

The software adds tools for inspecting clusters and their fee ordering, and changes replacement validation to require an improved mempool fee diagram. It also removes older static wallet fee settings and requires mining clients using its inter-process interface to update their schema. These changes affect node operators and mining software. Version 28.x and older reach end of life with this major release and no longer receive updates. The announcement describes node software behaviour and support policy; it does not promise a particular transaction fee or change Bitcoin’s issuance schedule. Bitcoin release notes.