onERC1155Received and onERC1155BatchReceived function shows not implemented error

Smart Contracts
1

Hi. Below is my code for an ERC1155 upgradeable contract which should be able to receive 1155 token and erc1155 token batches. Even though i have implemented the onERC1155Received and onERC1155BatchReceived functions it gives the following error for both the functions

TypeError: Contract "ERC1155" should be marked as abstract.
--> contracts/ERC1155.sol:13:1:
|
13 | contract ERC1155 is Initializable, ... eable, IERC1155ReceiverUpgradeable{
| ^ (Relevant source part starts here and spans across multiple lines).
Note: Missing implementation:
--> @openzeppelin/contracts-upgradeable/token/ERC1155/IERC1155ReceiverUpgradeable.sol:27:5:
|
27 | function onERC1155Received(
| ^ (Relevant source part starts here and spans across multiple lines).

Following is my code of the contract

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.4;

import "@openzeppelin/contracts-upgradeable/token/ERC1155/ERC1155Upgradeable.sol";

import "@openzeppelin/contracts-upgradeable/access/AccessControlUpgradeable.sol";

import "@openzeppelin/contracts-upgradeable/security/PausableUpgradeable.sol";

import "@openzeppelin/contracts-upgradeable/token/ERC1155/extensions/ERC1155BurnableUpgradeable.sol";

import "@openzeppelin/contracts-upgradeable/token/ERC1155/extensions/ERC1155SupplyUpgradeable.sol";

import "@openzeppelin/contracts-upgradeable/token/ERC1155/IERC1155ReceiverUpgradeable.sol";

import "@openzeppelin/contracts-upgradeable/proxy/utils/Initializable.sol";

contract ERC1155 is  Initializable, ERC1155Upgradeable, AccessControlUpgradeable, PausableUpgradeable, ERC1155BurnableUpgradeable, ERC1155SupplyUpgradeable, IERC1155ReceiverUpgradeable{

    bytes32 public constant URI_SETTER_ROLE = keccak256("URI_SETTER_ROLE");

    bytes32 public constant PAUSER_ROLE = keccak256("PAUSER_ROLE");

    bytes32 public constant MINTER_ROLE = keccak256("MINTER_ROLE");

    /// @custom:oz-upgrades-unsafe-allow constructor

    constructor() initializer {}

    function initialize() initializer public {

        __ERC1155_init("https://akriptt.com/token/");

        __AccessControl_init();

        __Pausable_init();

        __ERC1155Burnable_init();

        __ERC1155Supply_init();

        _grantRole(DEFAULT_ADMIN_ROLE, msg.sender);

        _grantRole(URI_SETTER_ROLE, msg.sender);

        _grantRole(PAUSER_ROLE, msg.sender);

        _grantRole(MINTER_ROLE, msg.sender);

    }

    function setURI(string memory newuri) public onlyRole(URI_SETTER_ROLE) {

        _setURI(newuri);

    }

    function pause() public onlyRole(PAUSER_ROLE) {

        _pause();

    }

    function unpause() public onlyRole(PAUSER_ROLE) {

        _unpause();

    }

    function mint(address account, uint256 id, uint256 amount, bytes memory data)

        public

        onlyRole(MINTER_ROLE)

    {

        _mint(account, id, amount, data);

    }

    function mintBatch(address to, uint256[] memory ids, uint256[] memory amounts, bytes memory data)

        public

        onlyRole(MINTER_ROLE)

    {

        _mintBatch(to, ids, amounts, data);

    }

    function _beforeTokenTransfer(address operator, address from, address to, uint256[] memory ids, uint256[] memory amounts, bytes memory data)

        internal

        whenNotPaused

        override(ERC1155Upgradeable, ERC1155SupplyUpgradeable)

    {

        super._beforeTokenTransfer(operator, from, to, ids, amounts, data);

    }

    // The following functions are overrides required by Solidity.

    function supportsInterface(bytes4 interfaceId)

        public

        view

        override(IERC165Upgradeable, ERC1155Upgradeable, AccessControlUpgradeable)

        returns (bool)

    {

        return super.supportsInterface(interfaceId);

    }

   

   function onERC1155Received(address operator, address from, uint256[] calldata ids, uint256[] calldata values, bytes calldata data

    ) external returns (bytes4) {

        return bytes4(keccak256("onERC1155Received(address,address,uint256,uint256,bytes)"));

    }

    function onERC1155BatchReceived(

        address operator,

        address from,

        uint256[] calldata ids,

        uint256[] calldata values,

        bytes calldata data

    ) external returns (bytes4){

        return bytes4(keccak256("onERC1155BatchReceived(address,address,uint256[],uint256[],bytes)"));

    }

}

Can someone help me in understanding what is causing this error.