# Upgrade to FungibleToken contract coming on testnet and mainnet **URL:** \ **Category:** Flow Protocol\ **Created:** [March 10, 2023, 4:54pm UTC](https://forum.flow.com/t/upgrade-to-fungibletoken-contract-coming-on-testnet-and-mainnet/4441 "2023-03-10T16:54:57Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![Destructor](https://avatars.discourse-cdn.com/v4/letter/d/58f4c7/32.png) [@Destructor](https://forum.flow.com/u/Destructor)\ **Post date:** [March 10, 2023, 4:54pm UTC](https://forum.flow.com/t/upgrade-to-fungibletoken-contract-coming-on-testnet-and-mainnet/4441/1 "2023-03-10T16:54:57Z")
We want to let you know that there will be an upgrade to the **FungibleToken** smart contract standard. This upgrade adds a new method for receivers to specify the vault types that they can receive. This will not cause a breaking change to any existing deployed Fungible Token contracts or contracts that have types that implement `FungibleToken.Receiver` because it includes a default implementation for the method. **Expected dates to get the changes in effect is as follows:** - CanaryNet: Wednesday, March 15th - Testnet: Thursday, March 16th And assuming that the upgrades on the canary and testnet go well, - Mainnet: Wednesday, March 22 (This date may be delayed) The `FungibleToken` code that will be used for the upgrade can be found in [this PR](https://github.com/onflow/flow-ft/pull/123). **Note** - We are open to changing the timeline if the community provides feedback on the suggested change. **Why This Change is Happening** - Adding type information to `FungibleToken.Receiver` capabilities has the potential to streamline the FT receiving process and minimize transaction failures. - The current `FungibleToken.Receiver` interface only contains the `deposit` method. It does not offer a clear-cut method for knowing the `Vault` types that a particular receiver can receive. To address this issue, `getSupportedVaultTypes` function was suggested. More details can be found in the [FLIP](https://github.com/onflow/flips/blob/fungibleToken-standard-improvement/flips/20230206-fungible-token-vault-type-discovery.md) **Action Required** - For any custom receivers like `TokenForwarding`, `FungibleTokenSwitchboard` contract or any resource in other contracts that conforms `FungibleToken.Receiver` should define a `getSupportedVaultTypes` function to return an array of `Vault` types that the `Receiver` can take in the `deposit()` method. Until this change is made, custom receivers will only return an empty dictionary for this method (`{}`) as the return value. The proposed interface features a default implementation of the `getSupportedVaultTypes()` function, ensuring that existing FTs will not encounter any breakage and will have a ready-made implementation available. This default implementation also eliminates the need for upgrading existing FTs, but they should still upgrade eventually for clarity purposes. In this [PR](https://github.com/onflow/flow-ft/pull/123/), the Flow team has also implemented the `getSupportedVaultTypes` function for the `FungibleTokenSwitchboard` and `TokenForwarding` contracts. These contracts will be upgraded at the same time as `FungibleToken` on their respective networks. If you have any questions regarding these changes, please ask in the PR comments, on Discord in the #developers channel, or reply here. ---
**Author:** ![flowjosh](https://sea2.discourse-cdn.com/flex022/user_avatar/forum.flow.com/flowjosh/32/362_2.png) [@flowjosh](https://forum.flow.com/u/flowjosh)\ **Post date:** [March 15, 2023, 7:07pm UTC](https://forum.flow.com/t/upgrade-to-fungibletoken-contract-coming-on-testnet-and-mainnet/4441/2 "2023-03-15T19:07:45Z")
The contract has been upgraded on Canary to account `0xee82856bf20e2aa6` ---
**Author:** ![flowjosh](https://sea2.discourse-cdn.com/flex022/user_avatar/forum.flow.com/flowjosh/32/362_2.png) [@flowjosh](https://forum.flow.com/u/flowjosh)\ **Post date:** [March 16, 2023, 6:39pm UTC](https://forum.flow.com/t/upgrade-to-fungibletoken-contract-coming-on-testnet-and-mainnet/4441/3 "2023-03-16T18:39:02Z")
These contracts have been updated on testnet: - `FungibleToken` - `0x9a0766d93b6608b7` - `FungibleTokenSwitchboard` - `0x9a0766d93b6608b7` - `TokenForwarding` - `0x51ea0e37c27a1f1a` ---
**Author:** ![dryrunner](https://sea2.discourse-cdn.com/flex022/user_avatar/forum.flow.com/dryrunner/32/641_2.png) [@dryrunner](https://forum.flow.com/u/dryrunner)\ **Post date:** [March 18, 2023, 9:37pm UTC](https://forum.flow.com/t/upgrade-to-fungibletoken-contract-coming-on-testnet-and-mainnet/4441/4 "2023-03-18T21:37:18Z")
Put a comment there: [https://github.com/onflow/flips/pull/69](https://github.com/onflow/flips/pull/69) ---
**Author:** ![bluesign](https://sea2.discourse-cdn.com/flex022/user_avatar/forum.flow.com/bluesign/32/1359_2.png) [@bluesign](https://forum.flow.com/u/bluesign)\ **Post date:** [March 20, 2023, 10:06am UTC](https://forum.flow.com/t/upgrade-to-fungibletoken-contract-coming-on-testnet-and-mainnet/4441/5 "2023-03-20T10:06:26Z")
I commented there [0], but also writing here: Why did we change the `getSupportedVaultTypes` signature to `pub fun getSupportedVaultTypes(): {Type: Bool}` from `pub fun getSupportedVaultTypes(): [Type]` ? This is pretty ugly also does not make any sense. [0] [https://github.com/onflow/flow-ft/pull/127](https://github.com/onflow/flow-ft/pull/127) ---
**Author:** ![flowjosh](https://sea2.discourse-cdn.com/flex022/user_avatar/forum.flow.com/flowjosh/32/362_2.png) [@flowjosh](https://forum.flow.com/u/flowjosh)\ **Post date:** [March 22, 2023, 5:15pm UTC](https://forum.flow.com/t/upgrade-to-fungibletoken-contract-coming-on-testnet-and-mainnet/4441/6 "2023-03-22T17:15:31Z")
These contracts have been updated on mainnet: - `FungibleToken` - `0xf233dcee88fe0abe` - `FungibleTokenSwitchboard` - `0xf233dcee88fe0abe` - `TokenForwarding` - `0xe544175ee0461c4b`