> For the complete documentation index, see [llms.txt](https://docs.fringe.fi/smart-contract-documentation/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.fringe.fi/smart-contract-documentation/openzeppelin/contracts-upgradeable/token/erc-777/ierc777recipientupgradeable.md).

# IERC 777 Recipient Upgradeable

*Interface of the ERC777TokensRecipient standard as defined in the EIP. Accounts can be notified of {IERC777} tokens being sent to them by having a contract implement this interface (contract holders can be their own implementer) and registering it on the <https://eips.ethereum.org/EIPS/eip-1820\\[ERC1820> global registry]. See {IERC1820Registry} and {ERC1820Implementer}.*

## Methods

### tokensReceived

```solidity
function tokensReceived(address operator, address from, address to, uint256 amount, bytes userData, bytes operatorData) external nonpayable
```

*Called by an {IERC777} token contract whenever tokens are being moved or created into a registered account (`to`). The type of operation is conveyed by `from` being the zero address or not. This call occurs after the token contract's state is updated, so {IERC777-balanceOf}, etc., can be used to query the post-operation state. This function may revert to prevent the operation from being executed.*

#### Parameters

| Name         | Type    | Description |
| ------------ | ------- | ----------- |
| operator     | address | undefined   |
| from         | address | undefined   |
| to           | address | undefined   |
| amount       | uint256 | undefined   |
| userData     | bytes   | undefined   |
| operatorData | bytes   | undefined   |