Bitcoin ABC 0.27.0 Release Notes

Bitcoin ABC version 0.27.0 is now available from:

This release includes the following features and fixes:

The softforks field from the getblockchaininfo RPC is deprecated. To keep using this field, use the -deprecatedrpc=softforks option. Note that this field has been empty for a long time and will remain empty until its eventual removal.
The ancestorcount, ancestorsize and ancestorcount fields from the listunspent RPC have been deprecated and will be removed in a future version. To keep using these fields, use the -deprecatedrpc=mempool_ancestors_descendants option.
The RPC server can process a limited number of simultaneous RPC requests. Previously, if this limit was exceeded, bitcoind would respond with status code 500 (HTTP_INTERNAL_SERVER_ERROR). Now it returns status code 503 (HTTP_SERVICE_UNAVAILABLE).

Network upgrade

At the MTP time of 1684152000 (May 15, 2023 12:00:00 UTC), the following changes will become activated:

New consensus rule: The nVersion field in CTransaction now must be either 1 or 2. This has been a policy rule (i.e. wallets already cannot use anything other than 1 or 2), but miners were still able to mine transactions with versions other than 1 and 2. Disallowing them by consensus allows us to use the version field for e.g. a new & scalable transaction format.
The chained transactions limit policy will no longer be enforced by the mempool. All the related RPC statistics and options will become irrelevant and should no longer be relied upon.
Miner fund moves from consensus rule to policy rule. This will allow future seamless upgrades such as changes to the miner fund without delaying until a flag day upgrade.
Bump automatic replay protection to the next upgrade, timestamp 1700049600 (Nov 15, 2023 12:00:00 UTC).