Anchor: Solana Account Initialization Issue - rust

Question

I'm using serum anchor framework for solana. I'm tring to initialize new account with #[account] attribute macro.
Each time i run anchor build i get the below error.
Error("the payer specified for an init constraint must be mutable.")
thread 'main' panicked at 'Code not parseable: Error("the payer specified for an init constraint must be mutable.")', lang/syn/src/idl/file.rs:360:58 note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
Following is the code snippet, where I'm attempting the account initialization
#[derive(Accounts)]
#[instruction(pool_nonce: u8, vault_nonce: u8)]
pub struct InitializePool<'info> {
/// CHECK: This is not dangerous because we don't read or write from this account
authority: UncheckedAccount<'info>,
#[account(
mut,
// constraint = lp_token_pool_vault.mint == LP_TOKEN_MINT_PUBKEY.parse::<Pubkey>().unwrap(),
constraint = lp_token_pool_vault.owner == pool_signer.key(),
)]
lp_token_pool_vault: Box<Account<'info, TokenAccount>>,
#[account(
mut,
// constraint = lp_token_depositor.mint == LP_TOKEN_MINT_PUBKEY.parse::<Pubkey>().unwrap()
)]
lp_token_depositor: Box<Account<'info, TokenAccount>>,
lp_token_deposit_authority: Signer<'info>,
reward_mint: Box<Account<'info, Mint>>,
#[account(
constraint = reward_vault.mint == reward_mint.key(),
constraint = reward_vault.owner == pool_signer.key(),
constraint = reward_vault.close_authority == COption::None,
)]
reward_vault: Box<Account<'info, TokenAccount>>,
#[account(
seeds = [
pool.to_account_info().key.as_ref()
],
bump,
)]
/// CHECK: This is not dangerous because we don't read or write from this account
pool_signer: UncheckedAccount<'info>,
#[account(
zero,
)]
pool: Box<Account<'info, Pool>>,
#[account(
init,
payer = owner,
seeds = [
owner.key.as_ref(),
pool.to_account_info().key.as_ref()
],
bump,
space = 10240,
)]
vault: Box<Account<'info, Vault>>,
owner: Signer<'info>,
token_program: Program<'info, Token>,
system_program: Program<'info, System>,
}

Answer 1

While initializing new account you need to pay fees and rent and by specifying payer in
#[account(
init,
payer = owner,
seeds = [
owner.key.as_ref(),
pool.to_account_info().key.as_ref()
],
bump,
space = 10240,
)]
vault: Box<Account<'info, Vault>>,
In order to modify payer account it has to be mutable.
We specify it as
#[account(mut)] // <== add this missing macro
owner: Signer<'info>,

Answer 2

#[derive(Accounts)]
pub struct Initialize<'info> {
#[account(init, payer = owner, space = 9000)]
pub base_account: Account<'info, BaseAccount>,
#[account(mut)]
pub owner: Signer<'info>,
pub system_program: Program<'info, System>,
}
you should set the payer one of the Signers in account like above