2.0.0-rc.2

2.0.0-rc.2 is the second release candidate for Anchor v2. Compared with rc1, it brings a TypeScript client built on Solana Kit, Agave 4.3-compatible Rust dependencies, transaction v1 support in LiteSVM tests, and improvements to instruction arguments and account validation.

These notes focus on the changes that affect existing applications. See the release changes and CHANGELOG for more detail. This is a prerelease; applications should test their migration before deploying.

How to upgrade

Using AVM

Install the prerelease from source:

avm install 2.0.0-rc.2 --from-source
avm use 2.0.0-rc.2

Without AVM

cargo install --git https://github.com/otter-sec/anchor --tag v2.0.0-rc.2 anchor-cli --locked

Update the Anchor dependencies your application uses:

[dependencies]
anchor-lang = "=2.0.0-rc.2"
anchor-spl = "=2.0.0-rc.2"

Update anchor-client to the same version if you use the Rust client. Keep any features your application already enables.

For the TypeScript client, use Node.js 22.12 or newer and install the explicit prerelease version:

npm install @anchor-lang/core@2.0.0-rc.2 @solana/kit@^8.3.0

Projects still importing @coral-xyz/anchor must switch to @anchor-lang/core. Moving from Anchor v1 also requires the v2 migration changes; updating package versions alone is not sufficient.

TypeScript client built on Solana Kit

The provider, instruction builders, account namespace, account resolver, event subscriptions, and serialization codecs now use Kit. Existing TypeScript applications need to update their client code:

Pass a Kit transaction signer as the provider wallet. A provider can take either cluster endpoints or an existing Kit client with rpc and rpcSubscriptions:

import { AnchorProvider, createLocalWallet } from "@anchor-lang/core";
import { createSolanaRpc, createSolanaRpcSubscriptions } from "@solana/kit";
 
const provider = new AnchorProvider(
  {
    rpc: createSolanaRpc("http://localhost:8899"),
    rpcSubscriptions: createSolanaRpcSubscriptions("ws://localhost:8900"),
  },
  createLocalWallet(),
);

createLocalWallet() reads the keypair file named by ANCHOR_WALLET. Use your application's Kit signer instead in a browser.

The default provider commitment is now confirmed. Event listeners use Kit subscriptions, and IDL fetching uses @solana-program/program-metadata.

The @anchor-lang/borsh and @anchor-lang/spl-* packages are no longer part of the client. Replace SPL helpers and Native.system() with the corresponding @solana-program/* packages. The former bytes, public-key, token, and hashing utilities have moved to Kit or those program packages.

Agave 4.3 dependencies and transaction v1 tests

The Rust dependency stack is aligned with the SDK crates used by Agave 4.3. Individual SDK crates have different version numbers; they are not all version 4.3.0.

anchor-v2-testing now uses LiteSVM 0.18 and re-exports it, so tests can import anchor_v2_testing::litesvm::LiteSVM without a separate LiteSVM dependency. To keep a prerelease test harness reproducible, pin the unpublished testing crate to the release tag:

[dev-dependencies]
anchor-v2-testing = { git = "https://github.com/otter-sec/anchor", tag = "v2.0.0-rc.2" }

LiteSVM can execute transaction v1 messages containing Anchor instructions. Select VersionedMessage::V1 explicitly and put resource limits in the message's TransactionConfig, rather than adding ComputeBudget instructions. Unset compute-unit and loaded-account-data limits are zero, so set both when constructing the message.

This enables local v1 testing; it does not imply that v1 transactions are enabled on every cluster. Check the target cluster's feature activation before sending them there.

Instruction arguments and serialization

The Wincode upgrade and serialization fixes restore support for BTreeMap, BTreeSet, and tuples on Rust serialization surfaces. Floating-point values, including NaN, are also accepted.

Wincode does not reproduce every v1 Borsh behavior:

• HashMap and HashSet use iteration order rather than Borsh's sorted order. Use ordered collections or explicitly sorted values when you need canonical encoding.
• NaN values are accepted rather than rejected. Validate floats explicitly if your application requires finite values.

These differences apply to instruction data, instruction constraint arguments, default events, and #[account(borsh)] data. Native map/set support in the IDL and TypeScript client remains future work; Rust serialization support does not imply that these types work end to end in a TS client.

Instruction introspection and account fixes

Sysvar<SysvarInstructions> now supports typed access to the instructions sysvar, allowing programs to inspect instructions in the current transaction. Pass the instructions sysvar account explicitly; unlike Clock and Rent, it cannot be loaded through a sysvar syscall.

Other fixes improve existing account and client behavior:

• Enum variants are emitted correctly in IDLs, and InitSpace handles generic enums and qualified type paths more reliably.
• Box<T> forwards foreign-owner initialization and signer/address IDL metadata.
• PDA signer remaining accounts work through CPI handles, while checked CPI validation uses the account's actual signer status.
• Explicit PDA bumps no longer trigger automatic client derivation; empty seed arrays work, and optional accounts cannot be used as PDA seeds.
• Imported bytemuck layouts with padding are rejected, and tail-slab allocation and resizing respect the header's minimum data length.

Deprecated Token-2022 CPI guard helpers have been removed. Applications using them must remove those CPI calls; the guard cannot be configured through CPI.