- [p2p] [\#3834](https://github.com/tendermint/tendermint/issues/3834) Do not write 'Couldn't connect to any seeds' error log if there are no seeds in config file
- [rpc] [\#3818](https://github.com/tendermint/tendermint/issues/3818) Make `max_body_bytes` and `max_header_bytes` configurable(@bluele)
- [mempool] [\#3826](https://github.com/tendermint/tendermint/issues/3826) Make `max_msg_bytes` configurable(@bluele)
- [blockchain] [\#3561](https://github.com/tendermint/tendermint/issues/3561) Add early version of the new blockchain reactor, which is supposed to be more modular and testable compared to the old version. To try it, you'll have to change `version` in the config file, [here](https://github.com/tendermint/tendermint/blob/master/config/toml.go#L303) NOTE: It's not ready for a production yet. For further information, see [ADR-40](https://github.com/tendermint/tendermint/blob/master/docs/architecture/adr-040-blockchain-reactor-refactor.md) & [ADR-43](https://github.com/tendermint/tendermint/blob/master/docs/architecture/adr-043-blockchain-riri-org.md)
### IMPROVEMENTS:
- [abci] [\#3809](https://github.com/tendermint/tendermint/issues/3809) Recover from application panics in `server/socket_server.go` to allow socket cleanup (@ruseinov)
- [rpc] [\#2252](https://github.com/tendermint/tendermint/issues/2252) Add `/broadcast_evidence` endpoint to submit double signing and other types of evidence
- [p2p] [\#3664](https://github.com/tendermint/tendermint/issues/3664) p2p/conn: reuse buffer when write/read from secret connection(@guagualvcha)
- [node] Add variadic argument to `NewNode` to support functional options, allowing the Node to be more easily customized.
- [node] Add variadic argument to `NewNode` to support functional options, allowing the Node to be more easily customized.
- [node][\#3730](https://github.com/tendermint/tendermint/pull/3730) Add `CustomReactors` option to `NewNode` allowing caller to pass
custom reactors to run inside Tendermint node (@ParthDesai)
- [abci] [\#2127](https://github.com/tendermint/tendermint/issues/2127)RequestCheckTx has a new field, `CheckTxType`, which can take values of `CheckTxType_New` and `CheckTxType_Recheck`, indicating whether this is a new tx being checked for the first time or whether this tx is being rechecked after a block commit. This allows applications to skip certain expensive operations, like signature checking, if they've already been done once. see [docs](https://github.com/tendermint/tendermint/blob/eddb433d7c082efbeaf8974413a36641519ee895/docs/spec/abci/apps.md#mempool-connection)
- [p2p] \#3834 Do not write 'Couldn't connect to any seeds' error log if there are no seeds in config file
- [abci] \#3809 Recover from application panics in `server/socket_server.go` to allow socket cleanup (@ruseinov)
- [rpc] \#2252 Add `/broadcast_evidence` endpoint to submit double signing and other types of evidence
- [rpc] \#3818 Make `max_body_bytes` and `max_header_bytes` configurable
- [p2p] \#3664 p2p/conn: reuse buffer when write/read from secret connection
- [mempool] \#3826 Make `max_msg_bytes` configurable
- [blockchain] \#3561 Add early version of the new blockchain reactor, which is supposed to be more modular and testable compared to the old version. To try it, you'll have to change `version` in the config file, [here](https://github.com/tendermint/tendermint/blob/master/config/toml.go#L303) NOTE: It's not ready for a production yet. For further information, see [ADR-40](https://github.com/tendermint/tendermint/blob/master/docs/architecture/adr-040-blockchain-reactor-refactor.md) & [ADR-43](https://github.com/tendermint/tendermint/blob/master/docs/architecture/adr-043-blockchain-riri-org.md)