InvalidProgramId when passing the correct program id

Question

I have a anchor program locally that runs perfectly with anchor typescript client, but while trying to access with rust's solana_client it throws this error:

AnchorError caused by account: system_program. Error Code: InvalidProgramId. Error Number: 3008. Error Message: Program ID was not as expected.

I have defined the same program id with:

let program_id = Pubkey::from_str("my_program_id").unwrap();

The weirdest part is that it even finds the correct instruction, so I'm completely clueless about this error message.

This is how I'm trying to call the instruction:

let instruction = Instruction::new_with_bytes(
    program_id,
    _r, // my instruction
    vec![
        AccountMeta::new(my_account.pubkey(), false),
        AccountMeta::new(payer.pubkey(), true),
        AccountMeta::new(program_id, false),
    ],
);

Answer 1

As silly as it sounds, the last account should be a solana system program id, and not my program id. This was the fix:

let solana_program_id = solana_sdk::system_program::id();

let instruction = Instruction::new_with_bytes(
    program_id,
    instruction,
    vec![
        AccountMeta::new(my_account.pubkey(), true),
        AccountMeta::new(payer.pubkey(), false),
        AccountMeta::new(solana_program_id, false),
    ],
);