"failed: An account required by the instruction is missing" transfer within contract

Question

This is the entire source code of the smart contract

use solana_program::{
    account_info::{next_account_info, AccountInfo},
    entrypoint,
    entrypoint::ProgramResult,
    msg,
    program_error::ProgramError,
    pubkey::Pubkey,
    system_instruction,
    program::invoke,
};
use borsh::{BorshDeserialize, BorshSerialize};
use std::str::FromStr;

// Define the recipient addresses as global constants
const RECIPIENT1: &str = "AmeQw3nHaRrrwaz4D2X4TdJUF3huqj6aAKsUwtp97yVF";
const RECIPIENT2: &str = "GCMNrkr4kvNXQ3iEis7GzNwa2pCwT9SkC1aLagzuNLcu";

// Define the account data structure
#[derive(BorshSerialize, BorshDeserialize, Debug)]
pub struct AccountData {
    pub balance: u64,
}

// Define the entry point
entrypoint!(process_instruction);

// The processor function
fn process_instruction(
    _program_id: &Pubkey,
    accounts: &[AccountInfo],
    instruction_data: &[u8],
) -> ProgramResult {
    let accounts_iter = &mut accounts.iter();
    let pda_account = next_account_info(accounts_iter)?;
    let user_account = next_account_info(accounts_iter)?;

    if !user_account.is_signer {
        return Err(ProgramError::MissingRequiredSignature);
    }

    if instruction_data.len() < 1 {
        return Err(ProgramError::InvalidInstructionData);
    }

    match instruction_data[0] {
        0 => deposit(pda_account, user_account, instruction_data),
        1 => get_balance(pda_account),
        _ => Err(ProgramError::InvalidInstructionData),
    }
}

fn deposit<'a>(
    pda_account: &AccountInfo<'a>,
    user_account: &AccountInfo<'a>,
    instruction_data: &[u8],
) -> ProgramResult {
    // Ensure the instruction data is at least 9 bytes (1 byte for the instruction, 8 bytes for the amount)
    if instruction_data.len() < 9 {
        return Err(ProgramError::InvalidInstructionData);
    }

    // Ensure the account data has at least 8 bytes
    if pda_account.data_len() < 8 {
        return Err(ProgramError::InvalidAccountData);
    }

    let amount = u64::from_le_bytes(instruction_data[1..9].try_into().map_err(|_| ProgramError::InvalidInstructionData)?);

    let mut account_data: AccountData = AccountData::try_from_slice(&pda_account.data.borrow())?;
    let new_balance = account_data.balance.checked_add(amount).ok_or(ProgramError::InvalidAccountData)?;
    account_data.balance = new_balance;
    account_data.serialize(&mut &mut pda_account.data.borrow_mut()[..])?;

    msg!("Deposited {} to {}", amount, pda_account.key);

    // Define the recipient addresses using the global constants
    let recipient1 = Pubkey::from_str(RECIPIENT1).map_err(|_| ProgramError::InvalidInstructionData)?;
    let recipient2 = Pubkey::from_str(RECIPIENT2).map_err(|_| ProgramError::InvalidInstructionData)?;

    // Calculate the amounts for each recipient
    let amount_recipient1 = amount * 40 / 100;
    let amount_recipient2 = amount - amount_recipient1; // Ensure the total is still equal to the original amount

    // Check if the user account has enough balance
    if **user_account.lamports.borrow() < amount {
        return Err(ProgramError::InsufficientFunds);
    }

    // Create the instructions to transfer SOL
    let transfer_instruction1 = system_instruction::transfer(
        user_account.key,
        &recipient1,
        amount_recipient1,
    );
    let transfer_instruction2 = system_instruction::transfer(
        user_account.key,
        &recipient2,
        amount_recipient2,
    );

    // Invoke the instructions
    invoke(
        &transfer_instruction1,
        &[user_account.clone(), pda_account.clone()],
    )?;
    invoke(
        &transfer_instruction2,
        &[user_account.clone(), pda_account.clone()],
    )?;

    msg!("Transferred {} to {}", amount_recipient1, recipient1);
    msg!("Transferred {} to {}", amount_recipient2, recipient2);

    Ok(())
}

fn get_balance(pda_account: &AccountInfo) -> ProgramResult {
    // Ensure the account data has at least 8 bytes
    if pda_account.data_len() < 8 {
        return Err(ProgramError::InvalidAccountData);
    }

    let account_data: AccountData = AccountData::try_from_slice(&pda_account.data.borrow())?;
    msg!("Balance of {} is {}", pda_account.key, account_data.balance);

    Ok(())
}

An exception occurred when calling the deposit method of the contract

Failed to deposit funds: SendTransactionError: failed to send transaction: Transaction simulation failed: Error processing Instruction 0: An account required by the instruction is missing

 logs: [
    'Program 2kC5Bx7a4H9gxv7PGsmRxVN9qRoQyFbxBV9xsqY4ayBh invoke [1]',
    'Program log: Deposited 1000 to 7k7c1n6MKqQ1S6V1ajTMNnNEmxBfgv5PikKpJeBEwAyY',
    'Instruction references an unknown account AmeQw3nHaRrrwaz4D2X4TdJUF3huqj6aAKsUwtp97yVF',
    'Program 2kC5Bx7a4H9gxv7PGsmRxVN9qRoQyFbxBV9xsqY4ayBh consumed 31559 of 200000 compute units',
    'Program 2kC5Bx7a4H9gxv7PGsmRxVN9qRoQyFbxBV9xsqY4ayBh failed: An account required by the instruction is missing'
  ]

Answer 1

The error you are encountering means you are trying to you are trying to transfer to an account you haven't specified on your client side.

Double-check to make sure that the user_pda and user_account addresses match the constant RECIPIENT addresses you declared. I think that's the reason your program is failing