# Upgrading Tendermint Core This guide provides instructions for upgrading to specific versions of Tendermint Core. ## v0.34.0 **Upgrading to Tendermint 0.34 requires a blockchain restart.** This release is not compatible with previous blockchains due to changes to the encoding format (see "Protocol Buffers," below) and the block header (see "Blockchain Protocol"). ### ABCI Changes * New ABCI methods (`ListSnapshots`, `LoadSnapshotChunk`, `OfferSnapshot`, and `ApplySnapshotChunk`) were added to support the new State Sync feature. Previously, syncing a new node to a preexisting network could take days; but with State Sync, new nodes are able to join a network in a matter of seconds. Read [the spec](https://docs.tendermint.com/master/spec/abci/apps.html#state-sync) if you want to learn more about State Sync, or if you'd like your application to use it. (If you don't want to support State Sync in your application, you can just implement these new ABCI methods as no-ops, leaving them empty.) * `KV.Pair` has been replaced with `abci.EventAttribute`. The `EventAttribute.Index` field allows ABCI applications to dictate which events should be indexed. * The blockchain can now start from an arbitrary initial height, provided to the application via `RequestInitChain.InitialHeight`. * ABCI evidence type is now an enum with two recognized types of evidence: `DUPLICATE_VOTE` and `LIGHT_CLIENT_ATTACK`. Applications should be able to handle these evidence types (i.e., through slashing or other accountability measures). * The [`PublicKey` type](https://github.com/tendermint/tendermint/blob/master/proto/tendermint/crypto/keys.proto#L13-L15) (used in ABCI as part of `ValidatorUpdate`) now uses a `oneof` protobuf type. Note that since Tendermint only supports ed25519 validator keys, there's only one option in the `oneof`. For more, see "Protocol Buffers," below. * The field `Proof`, on the ABCI type `ResponseQuery`, is now named `ProofOps`. For more, see "Crypto," below. ### P2P Protocol The default codec is now proto3, not amino. The schema files can be found in the `/proto` directory. For more, see "Protobuf," below. ### Blockchain Protocol * `Header#LastResultsHash`, which is the root hash of a Merkle tree built from `ResponseDeliverTx(Code, Data)` as of v0.34 also includes `GasWanted` and `GasUsed` fields. * Merkle hashes of empty trees previously returned nothing, but now return the hash of an empty input, to conform with [RFC-6962](https://tools.ietf.org/html/rfc6962). This mainly affects `Header#DataHash`, `Header#LastResultsHash`, and `Header#EvidenceHash`, which are often empty. Non-empty hashes can also be affected, e.g. if their inputs depend on other (empty) Merkle hashes, giving different results. ### Transaction Indexing Tendermint now relies on the application to tell it which transactions to index. This means that in the `config.toml`, generated by Tendermint, there is no longer a way to specify which transactions to index. `tx.height` & `tx.hash` will always be indexed when using the `kv` indexer. Applications must now choose to either a) enable indexing for all transactions, or b) allow node operators to decide which transactions to index. Applications can notify Tendermint to index a specific transaction by setting `Index: bool` to `true` in the Event Attribute: ```go []types.Event{ { Type: "app", Attributes: []types.EventAttribute{ {Key: []byte("creator"), Value: []byte("Cosmoshi Netowoko"), Index: true}, }, }, } ``` ### Protocol Buffers Tendermint 0.34 replaces Amino with Protocol Buffers for encoding. This migration is extensive and results in a number of changes, however, Tendermint only uses the types generated from Protocol Buffers for disk and wire serialization. **This means that these changes should not affect you as a Tendermint user.** However, Tendermint users and contributors may note the following changes: * Directory layout changes: All proto files have been moved under one directory, `/proto`. This is in line with the recommended file layout by [Buf](https://buf.build). For more, see the [Buf documentation](https://buf.build/docs/lint-checkers#file_layout). * ABCI Changes: As noted in the "ABCI Changes" section above, the `PublicKey` type now uses a `oneof` type. For more on the Protobuf changes, please see our [blog post on this migration](https://medium.com/tendermint/tendermint-0-34-protocol-buffers-and-you-8c40558939ae). ### Consensus Parameters Tendermint 0.34 includes new and updated consensus parameters. #### Version Parameters (New) * `AppVersion`, which is the version of the ABCI application. #### Evidence Parameters * `MaxNum`, which caps the total amount of evidence by a absolute number. The default is 50. ### Crypto #### Keys * Keys no longer include a type prefix. For example, ed25519 pubkeys have been renamed from `PubKeyEd25519` to `PubKey`. This reduces stutter (e.g., `ed25519.PubKey`). * Keys are now byte slices (`[]byte`) instead of byte arrays (`[]byte`). * The multisig functionality that was previously in Tendermint now has a new home within the Cosmos SDK: [`cosmos/cosmos-sdk/types/multisig`](https://github.com/cosmos/cosmos-sdk/blob/master/crypto/types/multisig/multisignature.go). * Similarly, secp256k1 has been removed from the Tendermint repo. There is still [a secp256k1 implementation in the Cosmos SDK](https://github.com/cosmos/cosmos-sdk/tree/443e0c1f89bd3730a731aea30453bd732f7efa35/crypto/keys/secp256k1), and we recommend you use that package for all your secp256k1 needs. #### `merkle` Package * `SimpleHashFromMap()` and `SimpleProofsFromMap()` were removed. * The prefix `Simple` has been removed. (For example, `SimpleProof` is now called `Proof`.) * All protobuf messages have been moved to the `/proto` directory. * The protobuf message `Proof` that contained multiple ProofOp's has been renamed to `ProofOps`. As noted above, this affects the ABCI type `ResponseQuery`: The field that was named Proof is now named `ProofOps`. * `HashFromByteSlices` and `ProofsFromByteSlices` now return a hash for empty inputs, to conform with [RFC-6962](https://tools.ietf.org/html/rfc6962). ### `libs` Package The `bech32` package has moved to the Cosmos SDK: [`cosmos/cosmos-sdk/types/bech32`](https://github.com/cosmos/cosmos-sdk/tree/4173ea5ebad906dd9b45325bed69b9c655504867/types/bech32). ### CLI The `tendermint lite` command has been renamed to `tendermint light` and has a slightly different API. See [the docs](https://docs.tendermint.com/master/tendermint-core/light-client-protocol.html#http-proxy) for details. ### Light Client We have a new, rewritten light client! You can [read more](https://medium.com/tendermint/everything-you-need-to-know-about-the-tendermint-light-client-f80d03856f98) about the justifications and details behind this change. Other user-relevant changes include: * The old `lite` package was removed; the new light client uses the `light` package. * The `Verifier` was broken up into two pieces: * Core verification logic (pure `VerifyX` functions) * `Client` object, which represents the complete light client * The new light clients stores headers & validator sets as `LightBlock`s * The RPC client can be found in the `/rpc` directory. * The HTTP(S) proxy is located in the `/proxy` directory. ### `state` Package * A new field `State.InitialHeight` has been added to record the initial chain height, which must be `1` (not `0`) if starting from height `1`. This can be configured via the genesis field `initial_height`. * The `state` package now has a `Store` interface. All functions in [state/store.go](https://github.com/tendermint/tendermint/blob/56911ee35298191c95ef1c7d3d5ec508237aaff4/state/store.go#L42-L42) are now part of the interface. The interface returns errors on all methods and can be used by calling `state.NewStore(dbm.DB)`. ### `privval` Package All requests are now accompanied by the chain ID from the network. This is a optional field and can be ignored by key management systems. It is recommended to check the chain ID if using the same key management system for multiple chains. ### RPC `/unsafe_start_cpu_profiler`, `/unsafe_stop_cpu_profiler` and `/unsafe_write_heap_profile` were removed. For profiling, please use the pprof server, which can be enabled through `--rpc.pprof_laddr=X` flag or `pprof_laddr=X` config setting in the rpc section. ## v0.33.4 ### Go API * `rpc/client` HTTP and local clients have been moved into `http` and `local` subpackages, and their constructors have been renamed to `New()`. ### Protobuf Changes When upgrading to version 0.33.4 you will have to fetch the `third_party` directory along with the updated proto files. ### Block Retention ResponseCommit added a field for block retention. The application can provide information to Tendermint on how to prune blocks. If an application would like to not prune any blocks pass a `0` in this field. ```proto message ResponseCommit { // reserve 1 bytes data = 2; // the Merkle root hash ++ uint64 retain_height = 3; // the oldest block height to retain ++ } ``` ## v0.33.0 This release is not compatible with previous blockchains due to commit becoming signatures only and fields in the header have been removed. ### Blockchain Protocol `TotalTxs` and `NumTxs` were removed from the header. `Commit` now consists mostly of just signatures. ```go type Commit struct { Height int64 Round int BlockID BlockID Signatures []CommitSig } ``` ```go type BlockIDFlag byte const ( // BlockIDFlagAbsent - no vote was received from a validator. BlockIDFlagAbsent BlockIDFlag = 0x01 // BlockIDFlagCommit - voted for the Commit.BlockID. BlockIDFlagCommit = 0x02 // BlockIDFlagNil - voted for nil. BlockIDFlagNil = 0x03 ) type CommitSig struct { BlockIDFlag BlockIDFlag ValidatorAddress Address Timestamp time.Time Signature []byte } ``` See [\#63](https://github.com/tendermint/spec/pull/63) for the complete spec change. ### P2P Protocol The secret connection now includes a transcript hashing. If you want to implement a handshake (or otherwise have an existing implementation), you'll need to make the same changes that were made [here](https://github.com/tendermint/tendermint/pull/3668). ### Config Changes You will need to generate a new config if you have used a prior version of tendermint. Tags have been entirely renamed throughout the codebase to events and there keys are called [compositeKeys](https://github.com/tendermint/tendermint/blob/6d05c531f7efef6f0619155cf10ae8557dd7832f/docs/app-dev/indexing-transactions.md). Evidence Params has been changed to include duration. * `consensus_params.evidence.max_age_duration`. * Renamed `consensus_params.evidence.max_age` to `max_age_num_blocks`. ### Go API * `libs/common` has been removed in favor of specific pkgs. * `async` * `service` * `rand` * `net` * `strings` * `cmap` * removal of `errors` pkg ### RPC Changes * `/validators` is now paginated (default: 30 vals per page) * `/block_results` response format updated [see RPC docs for details](https://docs.tendermint.com/master/rpc/#/Info/block_results) * Event suffix has been removed from the ID in event responses * IDs are now integers not `json-client-XYZ` ## v0.32.0 This release is compatible with previous blockchains, however the new ABCI Events mechanism may create some complexity for nodes wishing to continue operation with v0.32 from a previous version. There are some minor breaking changes to the RPC. ### Config Changes If you have `db_backend` set to `leveldb` in your config file, please change it to `goleveldb` or `cleveldb`. ### RPC Changes The default listen address for the RPC is now `127.0.0.1`. If you want to expose it publicly, you have to explicitly configure it. Note exposing the RPC to the public internet may not be safe - endpoints which return a lot of data may enable resource exhaustion attacks on your node, causing the process to crash. Any consumers of `/block_results` need to be mindful of the change in all field names from CamelCase to Snake case, eg. `results.DeliverTx` is now `results.deliver_tx`. This is a fix, but it's breaking. ### ABCI Changes ABCI responses which previously had a `Tags` field now have an `Events` field instead. The original `Tags` field was simply a list of key-value pairs, where each key effectively represented some attribute of an event occuring in the blockchain, like `sender`, `receiver`, or `amount`. However, it was difficult to represent the occurence of multiple events (for instance, multiple transfers) in a single list. The new `Events` field contains a list of `Event`, where each `Event` is itself a list of key-value pairs, allowing for more natural expression of multiple events in eg. a single DeliverTx or EndBlock. Note each `Event` also includes a `Type`, which is meant to categorize the event. For transaction indexing, the index key is prefixed with the event type: `{eventType}.{attributeKey}`. If the same event type and attribute key appear multiple times, the values are appended in a list. To make queries, include the event type as a prefix. For instance if you previously queried for `recipient = 'XYZ'`, and after the upgrade you name your event `transfer`, the new query would be for `transfer.recipient = 'XYZ'`. Note that transactions indexed on a node before upgrading to v0.32 will still be indexed using the old scheme. For instance, if a node upgraded at height 100, transactions before 100 would be queried with `recipient = 'XYZ'` and transactions after 100 would be queried with `transfer.recipient = 'XYZ'`. While this presents additional complexity to clients, it avoids the need to reindex. Of course, you can reset the node and sync from scratch to re-index entirely using the new scheme. We illustrate further with a more complete example. Prior to the update, suppose your `ResponseDeliverTx` look like: ```go abci.ResponseDeliverTx{ Tags: []kv.Pair{ {Key: []byte("sender"), Value: []byte("foo")}, {Key: []byte("recipient"), Value: []byte("bar")}, {Key: []byte("amount"), Value: []byte("35")}, } } ``` The following queries would match this transaction: ```go query.MustParse("tm.event = 'Tx' AND sender = 'foo'") query.MustParse("tm.event = 'Tx' AND recipient = 'bar'") query.MustParse("tm.event = 'Tx' AND sender = 'foo' AND recipient = 'bar'") ``` Following the upgrade, your `ResponseDeliverTx` would look something like: the following `Events`: ```go abci.ResponseDeliverTx{ Events: []abci.Event{ { Type: "transfer", Attributes: kv.Pairs{ {Key: []byte("sender"), Value: []byte("foo")}, {Key: []byte("recipient"), Value: []byte("bar")}, {Key: []byte("amount"), Value: []byte("35")}, }, } } ``` Now the following queries would match this transaction: ```go query.MustParse("tm.event = 'Tx' AND transfer.sender = 'foo'") query.MustParse("tm.event = 'Tx' AND transfer.recipient = 'bar'") query.MustParse("tm.event = 'Tx' AND transfer.sender = 'foo' AND transfer.recipient = 'bar'") ``` For further documentation on `Events`, see the [docs](https://github.com/tendermint/tendermint/blob/60827f75623b92eff132dc0eff5b49d2025c591e/docs/spec/abci/abci.md#events). ### Go Applications The ABCI Application interface changed slightly so the CheckTx and DeliverTx methods now take Request structs. The contents of these structs are just the raw tx bytes, which were previously passed in as the argument. ## v0.31.6 There are no breaking changes in this release except Go API of p2p and mempool packages. Hovewer, if you're using cleveldb, you'll need to change the compilation tag: Use `cleveldb` tag instead of `gcc` to compile Tendermint with CLevelDB or use `make build_c` / `make install_c` (full instructions can be found at ) ## v0.31.0 This release contains a breaking change to the behaviour of the pubsub system. It also contains some minor breaking changes in the Go API and ABCI. There are no changes to the block or p2p protocols, so v0.31.0 should work fine with blockchains created from the v0.30 series. ### RPC The pubsub no longer blocks on publishing. This may cause some WebSocket (WS) clients to stop working as expected. If your WS client is not consuming events fast enough, Tendermint can terminate the subscription. In this case, the WS client will receive an error with description: ```json { "jsonrpc": "2.0", "id": "{ID}#event", "error": { "code": -32000, "msg": "Server error", "data": "subscription was cancelled (reason: client is not pulling messages fast enough)" // or "subscription was cancelled (reason: Tendermint exited)" } } Additionally, there are now limits on the number of subscribers and subscriptions that can be active at once. See the new `rpc.max_subscription_clients` and `rpc.max_subscriptions_per_client` values to configure this. ``` ### Applications Simple rename of `ConsensusParams.BlockSize` to `ConsensusParams.Block`. The `ConsensusParams.Block.TimeIotaMS` field was also removed. It's configured in the ConsensusParsm in genesis. ### Go API See the [CHANGELOG](CHANGELOG.md). These are relatively straight forward. ## v0.30.0 This release contains a breaking change to both the block and p2p protocols, however it may be compatible with blockchains created with v0.29.0 depending on the chain history. If your blockchain has not included any pieces of evidence, or no piece of evidence has been included in more than one block, and if your application has never returned multiple updates for the same validator in a single block, then v0.30.0 will work fine with blockchains created with v0.29.0. The p2p protocol change is to fix the proposer selection algorithm again. Note that proposer selection is purely a p2p concern right now since the algorithm is only relevant during real time consensus. This change is thus compatible with v0.29.0, but all nodes must be upgraded to avoid disagreements on the proposer. ### Applications Applications must ensure they do not return duplicates in `ResponseEndBlock.ValidatorUpdates`. A pubkey must only appear once per set of updates. Duplicates will cause irrecoverable failure. If you have a very good reason why we shouldn't do this, please open an issue. ## v0.29.0 This release contains some breaking changes to the block and p2p protocols, and will not be compatible with any previous versions of the software, primarily due to changes in how various data structures are hashed. Any implementations of Tendermint blockchain verification, including lite clients, will need to be updated. For specific details: * [Merkle tree](https://github.com/tendermint/spec/blob/master/spec/blockchain/encoding.md#merkle-trees) * [ConsensusParams](https://github.com/tendermint/spec/blob/master/spec/blockchain/state.md#consensusparams) There was also a small change to field ordering in the vote struct. Any implementations of an out-of-process validator (like a Key-Management Server) will need to be updated. For specific details: * [Vote](https://github.com/tendermint/spec/blob/master/spec/consensus/signing.md#votes) Finally, the proposer selection algorithm continues to evolve. See the [work-in-progress specification](https://github.com/tendermint/tendermint/pull/3140). For everything else, please see the [CHANGELOG](./CHANGELOG.md#v0.29.0). ## v0.28.0 This release breaks the format for the `priv_validator.json` file and the protocol used for the external validator process. It is compatible with v0.27.0 blockchains (neither the BlockProtocol nor the P2PProtocol have changed). Please read carefully for details about upgrading. **Note:** Backup your `config/priv_validator.json` before proceeding. ### `priv_validator.json` The `config/priv_validator.json` is now two files: `config/priv_validator_key.json` and `data/priv_validator_state.json`. The former contains the key material, the later contains the details on the last message signed. When running v0.28.0 for the first time, it will back up any pre-existing `priv_validator.json` file and proceed to split it into the two new files. Upgrading should happen automatically without problem. To upgrade manually, use the provided `privValUpgrade.go` script, with exact paths for the old `priv_validator.json` and the locations for the two new files. It's recomended to use the default paths, of `config/priv_validator_key.json` and `data/priv_validator_state.json`, respectively: ```sh go run scripts/privValUpgrade.go ``` ### External validator signers The Unix and TCP implementations of the remote signing validator have been consolidated into a single implementation. Thus in both cases, the external process is expected to dial Tendermint. This is different from how Unix sockets used to work, where Tendermint dialed the external process. The `PubKeyMsg` was also split into separate `Request` and `Response` types for consistency with other messages. Note that the TCP sockets don't yet use a persistent key, so while they're encrypted, they can't yet be properly authenticated. See [#3105](https://github.com/tendermint/tendermint/issues/3105). Note the Unix socket has neither encryption nor authentication, but will add a shared-secret in [#3099](https://github.com/tendermint/tendermint/issues/3099). ## v0.27.0 This release contains some breaking changes to the block and p2p protocols, but does not change any core data structures, so it should be compatible with existing blockchains from the v0.26 series that only used Ed25519 validator keys. Blockchains using Secp256k1 for validators will not be compatible. This is due to the fact that we now enforce which key types validators can use as a consensus param. The default is Ed25519, and Secp256k1 must be activated explicitly. It is recommended to upgrade all nodes at once to avoid incompatibilities at the peer layer - namely, the heartbeat consensus message has been removed (only relevant if `create_empty_blocks=false` or `create_empty_blocks_interval > 0`), and the proposer selection algorithm has changed. Since proposer information is never included in the blockchain, this change only affects the peer layer. ### Go API Changes #### libs/db The ReverseIterator API has changed the meaning of `start` and `end`. Before, iteration was from `start` to `end`, where `start > end`. Now, iteration is from `end` to `start`, where `start < end`. The iterator also excludes `end`. This change allows a simplified and more intuitive logic, aligning the semantic meaning of `start` and `end` in the `Iterator` and `ReverseIterator`. ### Applications This release enforces a new consensus parameter, the ValidatorParams.PubKeyTypes. Applications must ensure that they only return validator updates with the allowed PubKeyTypes. If a validator update includes a pubkey type that is not included in the ConsensusParams.Validator.PubKeyTypes, block execution will fail and the consensus will halt. By default, only Ed25519 pubkeys may be used for validators. Enabling Secp256k1 requires explicit modification of the ConsensusParams. Please update your application accordingly (ie. restrict validators to only be able to use Ed25519 keys, or explicitly add additional key types to the genesis file). ## v0.26.0 This release contains a lot of changes to core data types and protocols. It is not compatible to the old versions and there is no straight forward way to update old data to be compatible with the new version. To reset the state do: ```sh tendermint unsafe_reset_all ``` Here we summarize some other notable changes to be mindful of. ### Config Changes All timeouts must be changed from integers to strings with their duration, for instance `flush_throttle_timeout = 100` would be changed to `flush_throttle_timeout = "100ms"` and `timeout_propose = 3000` would be changed to `timeout_propose = "3s"`. ### RPC Changes The default behaviour of `/abci_query` has been changed to not return a proof, and the name of the parameter that controls this has been changed from `trusted` to `prove`. To get proofs with your queries, ensure you set `prove=true`. Various version fields like `amino_version`, `p2p_version`, `consensus_version`, and `rpc_version` have been removed from the `node_info.other` and are consolidated under the tendermint semantic version (ie. `node_info.version`) and the new `block` and `p2p` protocol versions under `node_info.protocol_version`. ### ABCI Changes Field numbers were bumped in the `Header` and `ResponseInfo` messages to make room for new `version` fields. It should be straight forward to recompile the protobuf file for these changes. #### Proofs The `ResponseQuery.Proof` field is now structured as a `[]ProofOp` to support generalized Merkle tree constructions where the leaves of one Merkle tree are the root of another. If you don't need this functionality, and you used to return `` here, you should instead return a single `ProofOp` with just the `Data` field set: ```go []ProofOp{ ProofOp{ Data: , } } ``` For more information, see: * [ADR-026](https://github.com/tendermint/tendermint/blob/30519e8361c19f4bf320ef4d26288ebc621ad725/docs/architecture/adr-026-general-merkle-proof.md) * [Relevant ABCI documentation](https://github.com/tendermint/tendermint/blob/30519e8361c19f4bf320ef4d26288ebc621ad725/docs/spec/abci/apps.md#query-proofs) * [Description of keys](https://github.com/tendermint/tendermint/blob/30519e8361c19f4bf320ef4d26288ebc621ad725/crypto/merkle/proof_key_path.go#L14) ### Go API Changes #### crypto/merkle The `merkle.Hasher` interface was removed. Functions which used to take `Hasher` now simply take `[]byte`. This means that any objects being Merklized should be serialized before they are passed in. #### node The `node.RunForever` function was removed. Signal handling and running forever should instead be explicitly configured by the caller. See how we do it [here](https://github.com/tendermint/tendermint/blob/30519e8361c19f4bf320ef4d26288ebc621ad725/cmd/tendermint/commands/run_node.go#L60). ### Other All hashes, except for public key addresses, are now 32-bytes. ## v0.25.0 This release has minimal impact. If you use GasWanted in ABCI and want to enforce it, set the MaxGas in the genesis file (default is no max). ## v0.24.0 New 0.24.0 release contains a lot of changes to the state and types. It's not compatible to the old versions and there is no straight forward way to update old data to be compatible with the new version. To reset the state do: ```sh tendermint unsafe_reset_all ``` Here we summarize some other notable changes to be mindful of. ### Config changes `p2p.max_num_peers` was removed in favor of `p2p.max_num_inbound_peers` and `p2p.max_num_outbound_peers`. ```toml # Maximum number of inbound peers max_num_inbound_peers = 40 # Maximum number of outbound peers to connect to, excluding persistent peers max_num_outbound_peers = 10 ``` As you can see, the default ratio of inbound/outbound peers is 4/1. The reason is we want it to be easier for new nodes to connect to the network. You can tweak these parameters to alter the network topology. ### RPC Changes The result of `/commit` used to contain `header` and `commit` fields at the top level. These are now contained under the `signed_header` field. ### ABCI Changes The header has been upgraded and contains new fields, but none of the existing fields were changed, except their order. The `Validator` type was split into two, one containing an `Address` and one containing a `PubKey`. When processing `RequestBeginBlock`, use the `Validator` type, which contains just the `Address`. When returning `ResponseEndBlock`, use the `ValidatorUpdate` type, which contains just the `PubKey`. ### Validator Set Updates Validator set updates returned in ResponseEndBlock for height `H` used to take effect immediately at height `H+1`. Now they will be delayed one block, to take effect at height `H+2`. Note this means that the change will be seen by the ABCI app in the `RequestBeginBlock.LastCommitInfo` at block `H+3`. Apps were already required to maintain a map from validator addresses to pubkeys since v0.23 (when pubkeys were removed from RequestBeginBlock), but now they may need to track multiple validator sets at once to accomodate this delay. ### Block Size The `ConsensusParams.BlockSize.MaxTxs` was removed in favour of `ConsensusParams.BlockSize.MaxBytes`, which is now enforced. This means blocks are limitted only by byte-size, not by number of transactions.