v5.0.0-rc.0

• ERC1155Receiver: Removed in favor of ERC1155Holder. (#4450)

• TimelockController: Changed the role architecture to use DEFAULT_ADMIN_ROLE as the admin for all roles, instead of the bespoke TIMELOCK_ADMIN_ROLE that was used previously. This aligns with the general recommendation for AccessControl and makes the addition of new roles easier. Accordingly, the admin parameter and timelock will now be granted DEFAULT_ADMIN_ROLE instead of TIMELOCK_ADMIN_ROLE. (#3799)

• Use abi.encodeCall in place of abi.encodeWithSelector and abi.encodeWithSignature for improved type-checking of parameters (#4293)

• ERC2771Forwarder: Added deadline for expiring transactions, batching, and more secure handling of msg.value. (#4346)

• Governor: Refactored internals to implement common queuing logic in the core module of the Governor. Added queue and _queueOperations functions that act at different levels. Modules that implement queuing via timelocks are expected to override _queueOperations to implement the timelock-specific logic. Added _executeOperations as the equivalent for execution. (#4360)

• ERC20, ERC721, ERC1155: Deleted _beforeTokenTransfer and _afterTokenTransfer hooks, added a new internal _update function for customizations, and refactored all extensions using those hooks to use _update instead. (#3838, #3876, #4377)

• ERC1155Supply: add a totalSupply() function that returns the total amount of token circulating, this change will restrict the total tokens minted across all ids to 2**256-1 . (#3962)

• Ownable: Add an initialOwner parameter to the constructor, making the ownership initialization explicit. (#4267)

• ERC721: _approve no longer allows approving the owner of the tokenId. _setApprovalForAll no longer allows setting address(0) as an operator. (#4377)

• ERC721URIStorage: Allow setting the token URI prior to minting. (#4559)

• UUPSUpgradeable, TransparentUpgradeableProxy and ProxyAdmin: Removed upgradeTo and upgrade functions, and made upgradeToAndCall and upgradeAndCall ignore the data argument if it is empty. It is no longer possible to invoke the receive function (or send value with empty data) along with an upgrade. (#4382)

• ERC721URIStorage, ERC721Royalty: Stop resetting token-specific URI and royalties when burning. (#4561)

• Address: Removed the ability to customize error messages. A common custom error is always used if the underlying revert reason cannot be bubbled up. (#4502)

• Checkpoints: library moved from utils to utils/structs (#4275)

• SafeERC20: Removed safePermit in favor of documentation-only permit recommendations. (#4582)

• Governor: Optimized use of storage for proposal data (#4268)

• ERC1967Utils: Refactor the ERC1967Upgrade abstract contract as a library. (#4325)

• TransparentUpgradeableProxy: Admin is now stored in an immutable variable (set during construction) to avoid unnecessary storage reads on every proxy call. This removed the ability to ever change the admin. Transfer of the upgrade capability is exclusively handled through the ownership of the ProxyAdmin. (#4354)

• VestingWallet: Use Ownable instead of an immutable beneficiary. (#4508)

• ERC20: Remove Approval event previously emitted in transferFrom to indicate that part of the allowance was consumed. With this change, allowances are no longer reconstructible from events. See the code for guidelines on how to re-enable this event if needed. (#4370)

• Move the logic to validate ERC-1822 during an upgrade from ERC1967Utils to UUPSUpgradeable. (#4356)

• MessageHashUtils: Add a new library for creating message digest to be used along with signing or recovery such as ECDSA or ERC-1271. These functions are moved from the ECDSA library. (#4430)

• Replace revert strings and require statements with custom errors. (#4261)

• Nonces: Added a new contract to keep track of user nonces. Used for signatures in ERC20Permit, ERC20Votes, and ERC721Votes. (#3816)

• Switched to using explicit Solidity import statements. Some previously available symbols may now have to be separately imported. (#4399)

• Governor: Add support for casting votes with ERC-1271 signatures by using a bytes memory signature instead of r, s and v arguments in the castVoteBySig and castVoteWithReasonAndParamsBySig functions. (#4418)

• ERC721: Renamed _requireMinted to _requireOwned and added a return value with the current owner. Implemented ownerOf in terms of _requireOwned. (#4566)

• GovernorTimelockControl: Add the Governor instance address as part of the TimelockController operation salt to avoid operation id collisions between governors using the same TimelockController.

• Overrides are now used internally for a number of functions that were previously hardcoded to their default implementation in certain locations: ERC1155Supply.totalSupply, ERC721.ownerOf, ERC721.balanceOf and ERC721.totalSupply in ERC721Enumerable, ERC20.totalSupply in ERC20FlashMint, and ERC1967._getImplementation in ERC1967Proxy. (#4299)

• ProxyAdmin: Removed getProxyAdmin and getProxyImplementation getters. (#3820)

• Bump minimum compiler version required to 0.8.20 (#4288)

• ERC20Votes: Changed internal vote accounting to reusable Votes module previously used by ERC721Votes. Removed implicit ERC20Permit inheritance. Note that the DOMAIN_SEPARATOR getter was previously guaranteed to be available for ERC20Votes contracts, but is no longer available unless ERC20Permit is explicitly used; ERC-5267 support is included in ERC20Votes with EIP712 and is recommended as an alternative. (#3816)

• ERC20: Remove the non-standard increaseAllowance and decreaseAllowance functions. (#4585)

• Governor: Add voter and nonce parameters in signed ballots, to avoid forging signatures for random addresses, prevent signature replay, and allow invalidating signatures. Add voter as a new parameter in the castVoteBySig and castVoteWithReasonAndParamsBySig functions. (#4378)

• TransparentUpgradeableProxy: Removed admin and implementation getters, which were only callable by the proxy owner and thus not very useful. (#3820)

• ERC1155: Remove check for address zero in balanceOf. (#4263)

• ReentrancyGuard, Pausable: Moved to utils directory. (#4551)

• access: Move AccessControl extensions to a dedicated directory. (#4359)

• DoubleEndedQueue: refactor internal structure to use uint128 instead of int128. This has no effect on the library interface. (#4150)

• Strings: Rename toString(int256) to toStringSigned(int256). (#4330)

• BeaconProxy: Reject value in initialization unless a payable function is explicitly invoked. (#4382)

• Initializable: Use the namespaced storage pattern to avoid putting critical variables in slot 0. Allow reinitializer versions greater than 256. (#4460)

• GovernorTimelockAccess: Added a module to connect a governor with an...

v4.9.3

Note
This release contains a fix for GHSA-g4vp-m682-qqmp.

• ERC2771Context: Return the forwarder address whenever the msg.data of a call originating from a trusted forwarder is not long enough to contain the request signer address (i.e. msg.data.length is less than 20 bytes), as specified by ERC-2771. (#4481)
• ERC2771Context: Prevent revert in _msgData() when a call originating from a trusted forwarder is not long enough to contain the request signer address (i.e. msg.data.length is less than 20 bytes). Return the full calldata in that case. (#4484)

v4.9.2

Note
This release contains a fix for GHSA-wprv-93r4-jj2p.

• MerkleProof: Fix a bug in processMultiProof and processMultiProofCalldata that allows proving arbitrary leaves if the tree contains a node with value 0 at depth 1.

v4.9.1

Note
This release contains a fix for GHSA-5h3x-9wvq-w4m2.

• Governor: Add a mechanism to restrict the address of the proposer using a suffix in the description.

v4.9.0

• ReentrancyGuard: Add a _reentrancyGuardEntered function to expose the guard status. (#3714)
• ERC721Wrapper: add a new extension of the ERC721 token which wraps an underlying token. Deposit and withdraw guarantee that the ownership of each token is backed by a corresponding underlying token with the same identifier. (#3863)
• EnumerableMap: add a keys() function that returns an array containing all the keys. (#3920)
• Governor: add a public cancel(uint256) function. (#3983)
• Governor: Enable timestamp operation for blockchains without a stable block time. This is achieved by connecting a Governor's internal clock to match a voting token's EIP-6372 interface. (#3934)
• Strings: add equal method. (#3774)
• IERC5313: Add an interface for EIP-5313 that is now final. (#4013)
• IERC4906: Add an interface for ERC-4906 that is now Final. (#4012)
• StorageSlot: Add support for string and bytes. (#4008)
• Votes, ERC20Votes, ERC721Votes: support timestamp checkpointing using EIP-6372. (#3934)
• ERC4626: Add mitigation to the inflation attack through virtual shares and assets. (#3979)
• Strings: add toString method for signed integers. (#3773)
• ERC20Wrapper: Make the underlying variable private and add a public accessor. (#4029)
• EIP712: add EIP-5267 support for better domain discovery. (#3969)
• AccessControlDefaultAdminRules: Add an extension of AccessControl with additional security rules for the DEFAULT_ADMIN_ROLE. (#4009)
• SignatureChecker: Add isValidERC1271SignatureNow for checking a signature directly against a smart contract using ERC-1271. (#3932)
• SafeERC20: Add a forceApprove function to improve compatibility with tokens behaving like USDT. (#4067)
• ERC1967Upgrade: removed contract-wide oz-upgrades-unsafe-allow delegatecall annotation, replaced by granular annotation in UUPSUpgradeable. (#3971)
• ERC20Wrapper: self wrapping and deposit by the wrapper itself are now explicitly forbidden. (#4100)
• ECDSA: optimize bytes32 computation by using assembly instead of abi.encodePacked. (#3853)
• ERC721URIStorage: Emit ERC-4906 MetadataUpdate in _setTokenURI. (#4012)
• ShortStrings: Added a library for handling short strings in a gas efficient way, with fallback to storage for longer strings. (#4023)
• SignatureChecker: Allow return data length greater than 32 from EIP-1271 signers. (#4038)
• UUPSUpgradeable: added granular oz-upgrades-unsafe-allow-reachable annotation to improve upgrade safety checks on latest version of the Upgrades Plugins (starting with @openzeppelin/[email protected]). (#3971)
• Initializable: optimize _disableInitializers by using != instead of <. (#3787)
• Ownable2Step: make acceptOwnership public virtual to enable usecases that require overriding it. (#3960)
• UUPSUpgradeable.sol: Change visibility to the functions upgradeTo and upgradeToAndCall from external to public. (#3959)
• TimelockController: Add the CallSalt event to emit on operation schedule. (#4001)
• Reformatted codebase with latest version of Prettier Solidity. (#3898)
• Math: optimize log256 rounding check. (#3745)
• ERC20Votes: optimize by using unchecked arithmetic. (#3748)
• Multicall: annotate multicall function as upgrade safe to not raise a flag for its delegatecall. (#3961)
• ERC20Pausable, ERC721Pausable, ERC1155Pausable: Add note regarding missing public pausing functionality (#4007)
• ECDSA: Add a function toDataWithIntendedValidatorHash that encodes data with version 0x00 following EIP-191. (#4063)
• MerkleProof: optimize by using unchecked arithmetic. (#3745)

Breaking changes

• EIP712: Addition of ERC5267 support requires support for user defined value types, which was released in Solidity version 0.8.8. This requires a pragma change from ^0.8.0 to ^0.8.8.
• EIP712: Optimization of the cache for the upgradeable version affects the way name and version are set. This is no longer done through an initializer, and is instead part of the implementation's constructor. As a consequence, all proxies using the same implementation will necessarily share the same name and version. Additionally, an implementation upgrade risks changing the EIP712 domain unless the same name and version are used when deploying the new implementation contract.

Deprecations

• ERC20Permit: Added the file IERC20Permit.sol and ERC20Permit.sol and deprecated draft-IERC20Permit.sol and draft-ERC20Permit.sol since EIP-2612 is no longer a Draft. Developers are encouraged to update their imports. (#3793)
• Timers: The Timers library is now deprecated and will be removed in the next major release. (#4062)
• ERC777: The ERC777 token standard is no longer supported by OpenZeppelin. Our implementation is now deprecated and will be removed in the next major release. The corresponding standard interfaces remain available. (#4066)
• ERC1820Implementer: The ERC1820 pseudo-introspection mechanism is no longer supported by OpenZeppelin. Our implementation is now deprecated and will be removed in the next major release. The corresponding standard interfaces remain available. (#4066)

v4.9.0-rc.0

• ReentrancyGuard: Add a _reentrancyGuardEntered function to expose the guard status. (#3714)
• ERC721Wrapper: add a new extension of the ERC721 token which wraps an underlying token. Deposit and withdraw guarantee that the ownership of each token is backed by a corresponding underlying token with the same identifier. (#3863)
• EnumerableMap: add a keys() function that returns an array containing all the keys. (#3920)
• Governor: add a public cancel(uint256) function. (#3983)
• Governor: Enable timestamp operation for blockchains without a stable block time. This is achieved by connecting a Governor's internal clock to match a voting token's EIP-6372 interface. (#3934)
• Strings: add equal method. (#3774)
• IERC5313: Add an interface for EIP-5313 that is now final. (#4013)
• IERC4906: Add an interface for ERC-4906 that is now Final. (#4012)
• StorageSlot: Add support for string and bytes. (#4008)
• Votes, ERC20Votes, ERC721Votes: support timestamp checkpointing using EIP-6372. (#3934)
• ERC4626: Add mitigation to the inflation attack through virtual shares and assets. (#3979)
• Strings: add toString method for signed integers. (#3773)
• ERC20Wrapper: Make the underlying variable private and add a public accessor. (#4029)
• EIP712: add EIP-5267 support for better domain discovery. (#3969)
• AccessControlDefaultAdminRules: Add an extension of AccessControl with additional security rules for the DEFAULT_ADMIN_ROLE. (#4009)
• SignatureChecker: Add isValidERC1271SignatureNow for checking a signature directly against a smart contract using ERC-1271. (#3932)
• SafeERC20: Add a forceApprove function to improve compatibility with tokens behaving like USDT. (#4067)
• ERC1967Upgrade: removed contract-wide oz-upgrades-unsafe-allow delegatecall annotation, replaced by granular annotation in UUPSUpgradeable. (#3971)
• ERC20Wrapper: self wrapping and deposit by the wrapper itself are now explicitelly forbiden. (#4100)
• ECDSA: optimize bytes32 computation by using assembly instead of abi.encodePacked. (#3853)
• ERC721URIStorage: Emit ERC-4906 MetadataUpdate in _setTokenURI. (#4012)
• ShortStrings: Added a library for handling short strings in a gas efficient way, with fallback to storage for longer strings. (#4023)
• SignatureChecker: Allow return data length greater than 32 from EIP-1271 signers. (#4038)
• UUPSUpgradeable: added granular oz-upgrades-unsafe-allow-reachable annotation to improve upgrade safety checks on latest version of the Upgrades Plugins (starting with @openzeppelin/[email protected]). (#3971)
• Initializable: optimize _disableInitializers by using != instead of <. (#3787)
• Ownable2Step: make acceptOwnership public virtual to enable usecases that require overriding it. (#3960)
• UUPSUpgradeable.sol: Change visibility to the functions upgradeTo and upgradeToAndCall from external to public. (#3959)
• TimelockController: Add the CallSalt event to emit on operation schedule. (#4001)
• Reformatted codebase with latest version of Prettier Solidity. (#3898)
• Math: optimize log256 rounding check. (#3745)
• ERC20Votes: optimize by using unchecked arithmetic. (#3748)
• Multicall: annotate multicall function as upgrade safe to not raise a flag for its delegatecall. (#3961)
• ERC20Pausable, ERC721Pausable, ERC1155Pausable: Add note regarding missing public pausing functionality (#4007)
• ECDSA: Add a function toDataWithIntendedValidatorHash that encodes data with version 0x00 following EIP-191. (#4063)
• MerkleProof: optimize by using unchecked arithmetic. (#3745)

Breaking changes

• EIP712: Addition of ERC5267 support requires support for user defined value types, which was released in Solidity version 0.8.8. This requires a pragma change from ^0.8.0 to ^0.8.8.
• EIP712: Optimization of the cache for the upgradeable version affects the way name and version are set. This is no longer done through an initializer, and is instead part of the implementation's constructor. As a consequence, all proxies using the same implementation will necessarily share the same name and version. Additionally, an implementation upgrade risks changing the EIP712 domain unless the same name and version are used when deploying the new implementation contract.

Deprecations

• ERC20Permit: Added the file IERC20Permit.sol and ERC20Permit.sol and deprecated draft-IERC20Permit.sol and draft-ERC20Permit.sol since EIP-2612 is no longer a Draft. Developers are encouraged to update their imports. (#3793)
• Timers: The Timers library is now deprecated and will be removed in the next major release. (#4062)
• ERC777: The ERC777 token standard is no longer supported by OpenZeppelin. Our implementation is now deprecated and will be removed in the next major release. The corresponding standard interfaces remain available. (#4066)
• ERC1820Implementer: The ERC1820 pseudo-introspection mechanism is no longer supported by OpenZeppelin. Our implementation is now deprecated and will be removed in the next major release. The corresponding standard interfaces remain available. (#4066)

v4.8.3

Note
This release contains fixes for GHSA-mx2q-35m2-x2rh and GHSA-93hq-5wgc-jc82.

• GovernorCompatibilityBravo: Fix encoding of proposal data when signatures are missing.
• TransparentUpgradeableProxy: Fix transparency in case of selector clash with non-decodable calldata or payable mutability. (#4154)

v4.8.2

Note
This release contains a fix for GHSA-878m-3g6q-594q.

• ERC721Consecutive: Fixed a bug when _mintConsecutive is used for batches of size 1 that could lead to balance overflow. Refer to the breaking changes section in the changelog for a note on the behavior of ERC721._beforeTokenTransfer.

Breaking changes

• ERC721: The internal function _beforeTokenTransfer no longer updates balances, which it previously did when batchSize was greater than 1. This change has no consequence unless a custom ERC721 extension is explicitly invoking _beforeTokenTransfer. Balance updates in extensions must now be done explicitly using __unsafe_increaseBalance, with a name that indicates that there is an invariant that has to be manually verified.

v4.8.1

• ERC4626: Use staticcall instead of call when fetching underlying ERC-20 decimals. (#3943)

v4.8.0

Note
Don't miss the section on Breaking changes at the end.

• TimelockController: Added a new admin constructor parameter that is assigned the admin role instead of the deployer account. (#3722)
• Initializable: add internal functions _getInitializedVersion and _isInitializing (#3598)
• ERC165Checker: add supportsERC165InterfaceUnchecked for consulting individual interfaces without the full ERC165 protocol. (#3339)
• Address: optimize functionCall by calling functionCallWithValue directly. (#3468)
• Address: optimize functionCall functions by checking contract size only if there is no returned data. (#3469)
• Governor: make the relay function payable, and add support for EOA payments. (#3730)
• GovernorCompatibilityBravo: remove unused using statements. (#3506)
• ERC20: optimize _transfer, _mint and _burn by using unchecked arithmetic when possible. (#3513)
• ERC20Votes, ERC721Votes: optimize getPastVotes for looking up recent checkpoints. (#3673)
• ERC20FlashMint: add an internal _flashFee function for overriding. (#3551)
• ERC4626: use the same decimals() as the underlying asset by default (if available). (#3639)
• ERC4626: add internal _initialConvertToShares and _initialConvertToAssets functions to customize empty vaults behavior. (#3639)
• ERC721: optimize transfers by making approval clearing implicit instead of emitting an event. (#3481)
• ERC721: optimize burn by making approval clearing implicit instead of emitting an event. (#3538)
• ERC721: Fix balance accounting when a custom _beforeTokenTransfer hook results in a transfer of the token under consideration. (#3611)
• ERC721: use unchecked arithmetic for balance updates. (#3524)
• ERC721Consecutive: Implementation of EIP-2309 that allows batch minting of ERC721 tokens during construction. (#3311)
• ReentrancyGuard: Reduce code size impact of the modifier by using internal functions. (#3515)
• SafeCast: optimize downcasting of signed integers. (#3565)
• ECDSA: Remove redundant check on the v value. (#3591)
• VestingWallet: add releasable getters. (#3580)
• VestingWallet: remove unused library Math.sol. (#3605)
• VestingWallet: make constructor payable. (#3665)
• Create2: optimize address computation by using assembly instead of abi.encodePacked. (#3600)
• Clones: optimized the assembly to use only the scratch space during deployments, and optimized predictDeterministicAddress to use fewer operations. (#3640)
• Checkpoints: Use procedural generation to support multiple key/value lengths. (#3589)
• Checkpoints: Add new lookup mechanisms. (#3589)
• Arrays: Add unsafeAccess functions that allow reading and writing to an element in a storage array bypassing Solidity's "out-of-bounds" check. (#3589)
• Strings: optimize toString. (#3573)
• Ownable2Step: extension of Ownable that makes the ownership transfers a two step process. (#3620)
• Math and SignedMath: optimize function max by using > instead of >=. (#3679)
• Math: Add log2, log10 and log256. (#3670)
• Arbitrum: Update the vendored arbitrum contracts to match the nitro upgrade. (#3692)

Breaking changes

• ERC721: In order to add support for batch minting via ERC721Consecutive it was necessary to make a minor breaking change in the internal interface of ERC721. Namely, the hooks _beforeTokenTransfer and _afterTokenTransfer have one additional argument that may need to be added to overrides:

 function _beforeTokenTransfer(
     address from,
     address to,
     uint256 tokenId,
+    uint256 batchSize
 ) internal virtual override

• ERC4626: Conversion from shares to assets (and vice-versa) in an empty vault used to consider the possible mismatch between the underlying asset's and the vault's decimals. This initial conversion rate is now set to 1-to-1 irrespective of decimals, which are meant for usability purposes only. The vault now uses the assets decimals by default, so off-chain the numbers should appear the same. Developers overriding the vault decimals to a value that does not match the underlying asset may want to override the _initialConvertToShares and _initialConvertToAssets to replicate the previous behavior.

• TimelockController: During deployment, the TimelockController used to grant the TIMELOCK_ADMIN_ROLE to the deployer and to the timelock itself. The deployer was then expected to renounce this role once configuration of the timelock is over. Failing to renounce that role allows the deployer to change the timelock permissions (but not to bypass the delay for any time-locked actions). The role is no longer given to the deployer by default. A new parameter admin can be set to a non-zero address to grant the admin role during construction (to the deployer or any other address). Just like previously, this admin role should be renounced after configuration. If this param is given address(0), the role is not allocated and doesn't need to be revoked. In any case, the timelock itself continues to have this role.

Deprecations

• EIP712: Added the file EIP712.sol and deprecated draft-EIP712.sol since the EIP is no longer a Draft. Developers are encouraged to update their imports. (#3621)

-import "@openzeppelin/contracts/utils/cryptography/draft-EIP712.sol";
+import "@openzeppelin/contracts/utils/cryptography/EIP712.sol";

• ERC721Votes: Added the file ERC721Votes.sol and deprecated draft-ERC721Votes.sol since it no longer depends on a Draft EIP (EIP-712). Developers are encouraged to update their imports. (#3699)

-import "@openzeppelin/contracts/token/ERC721/extensions/draft-ERC721Votes.sol";
+import "@openzeppelin/contracts/token/ERC721/extensions/ERC721Votes.sol";

ERC-721 Compatibility Note

ERC-721 integrators that interpret contract state from events should make sure that they implement the clearing of approval that is implicit in every transfer according to the EIP. Previous versions of OpenZeppelin Contracts emitted an explicit Approval event even though it was not required by the specification, and this is no longer the case.

With the new ERC721Consecutive extension, the internal workings of ERC721 are slightly changed. Custom extensions to ERC721 should be reviewed to ensure they remain correct. The internal functions that should be considered are _ownerOf (new), _beforeTokenTransfer, and _afterTokenTransfer.