Error Code: ConstraintMut. Error Number: 2000. Error Message: A mut constraint was violated.'

Question

failed: custom program error: 0x7d0'

pub fn bid(ctx: Context<Bid>, price: u64) -> Result<()> {
    let auction = &ctx.accounts.auction;

    let bidder = &mut ctx.accounts.bidder;

    //
    // Check bidder's balance against auction's price.
    //
    if price < auction.price {
        return Err(error!(MarketError::InsufficientMoney));
    }

    if (Clock::get()?.unix_timestamp as u128) > auction.end_time {
        return Err(error!(MarketError::AuctionEnded));
    }


    //if refund_receiver exist return the money
    if auction.refund_receiver != Pubkey::default() {

        
        **ctx.accounts.auction.to_account_info().try_borrow_mut_lamports()?  -= auction.price;
        **ctx.accounts.refund_receiver.try_borrow_mut_lamports()? += auction.price;


    }

    // Transfer bid price to auction  account

    anchor_lang::solana_program::program::invoke(
    &anchor_lang::solana_program::system_instruction::transfer(
        &bidder.to_account_info().key(),
        &auction.to_account_info().key(),
        price
    ),
    &[
        bidder.to_account_info(),
        auction.to_account_info(),
        ctx.accounts.system_program.to_account_info()
    ]
    )?;


    //update the auction info

    let auction = &mut ctx.accounts.auction;
    auction.refund_receiver = ctx.accounts.bidder.key();
    auction.price = price;  

    Ok(())

  
}

this is my function..

#[derive(Accounts)]
pub struct Bid<'info> {
    #[account(
        mut,
        seeds = [
            b"auction",
            mint_key.key.as_ref(),
        ],
        bump,
        has_one = creator
    )]
    pub auction: Account<'info, Auction>,

    /// CHECK: This account's address is only used.
    pub mint_key: AccountInfo<'info>,

    /// CHECK: This account's address is only used.
    pub creator: AccountInfo<'info>,

    #[account(mut)]
    pub bidder: Signer<'info>,

    /// CHECK: This account's address is only used.
    #[account(mut)]
    pub refund_receiver: AccountInfo<'info>,

    pub system_program: Program<'info, System>,
    pub token_program: Program<'info, Token>,
    pub associated_token_program: Program<'info, AssociatedToken>,
}

this is the context i am providing.

await program.methods.bid(
      new BN(price)
    ).accounts({
      auction: auctionAccount,
      mintKey: mintKey,
      creator: ownerKey,
      bidder: bidder.key.publicKey,
      refundReceiver: auction.refundReceiver,
    }).rpc();

and this is how i am calling the program.. I am unable to figure out where the code is going wrong..!!!?? if there is a better way to do it plss suggest...

Answer 1

Just ran into the same error. The issue (in my case) was my IDL was out-of-sync with the program I invoking on dev-net. The program was expecting a mutable account but the IDL had the account marked as immutable. The up-to-date IDL was still sitting in my target folder generated by anchor & I had not copied it to my JS build. Hope this helps.

Answer 2

The only inconsistency I see is that at the beginning you initialize an auction variable without &mut while your account is well mut (while bidder you initialize it well with &mut) and further down, you re-initialize the auction variable with &mut

Answer 3

Adding my answer here for anyone who finds themselves in a similar situation with a different solution - In my case, the account I was passing to the function was a non-existant account (it existed on mainnet but not devnet) and resulted in this error.