# Why the ERG monitor accepts a 9-prefix P2PK and not the P2S coinbase script

On Ergo mainnet a 9-address is P2PK. Protocol mining rewards lock in P2S. 2Miners’ ERG payout example starts with 9. The monitor looks up that pool payout address only.

- Canonical: https://iotahome.site/en/learn/erg-p2pk-address-monitoring
- Publisher: IOTA Watch
- Topics: Ergo
- Published: 2026-10-24
- Updated: 2026-10-24

## At a glance

Paste the 9-prefix ERG receive address from your wallet into the [ERG monitor](https://iotahome.site/en/projects/erg). P2S is the script that locks protocol rewards, not the pool payout this page wants.

## Address classes

| Class | What the docs say | This monitor |
| --- | --- | --- |
| Mainnet P2PK (starts with 9) | A 9-prefix is always mainnet P2PK | Accepted, then the pool payout account is queried |
| P2SH | Mainnet example starts with 8 | Not accepted |
| P2S | Protocol mining rewards lock here; prefix is not fixed | Not accepted. This is not the pool payout address |
| Testnet | The docs’ example starts with 3. This page does not look it up | Not accepted |

The monitor wants the address the pool pays ERG to, not the script that locks protocol rewards inside a block. Ergo’s address docs state that a mainnet address starting with 9 is P2PK, and that mining rewards go to a different class, P2S. The same page states that an address starting with 9 is always a P2PK address on mainnet. The 2Miners ERG help page tells you to create an ERG wallet for payouts, shows an ERG example that starts with 9, and also allows BTC or TON. A P2PK address can be the pool payout recipient. A P2S coinbase script does not imply that P2PK cannot receive those payouts.

## How to read the prefix

Read the prefix. You do not need to unpack the bytes inside. Mainnet P2PK starts with 9. The docs’ P2SH example starts with 8, and the testnet P2PK example starts with 3. P2S is the class that locks protocol mining rewards, and its prefix is not fixed. A string that fails the check is not sent to the pool.

## What to check before you paste

- Copy the ERG receive address from the official Ergo desktop wallet, Ergo Mobile Wallet, or an exchange the help page names for ERG. Those are the channels that page recommends for ERG, rather than a BTC deposit string.

- Keep only a mainnet receive address that starts with 9. A string starting with 8 matches the docs’ P2SH example. A testnet P2PK example starting with 3 is not this page.

- Do not rewrite another address so it starts with 9 just to pass the box. The rewritten string will not match.

## If it is refused or the wrong account opens

- The box refuses the string. Copy it from the wallet again. A 9 plus a short tail, or a character outside Base58 such as 0, O, I, or l, is not this P2PK.

- The miner is paying BTC or TON. That is another payout coin. This monitor cannot read those destinations. Check the payout coin you actually chose on the pool account page. If mining already pays BTC or TON, do not change the miner user field so this page can open. Paste a string here only when the payout address is already an ERG address that starts with 9.

- The account opens and the balance is the pool ledger, not every on-chain box. This page reads the public account for this payout address on erg.2miners.com. It does not list P2S coinbase boxes.

## Illustrative shapes, not a real transfer

The docs’ own mainnet shapes are enough to remember: P2PK like 9fRA…, P2SH like 8UAp…, P2S like 4MQy… or BxKB…. Paste only the 9fRA class after it checks out. Those fragments show the class. They are not your balance.

Next, open the [ERG monitor](https://iotahome.site/en/projects/erg). How that string sits in the miner user field is in [which address to paste](https://iotahome.site/en/learn/erg-mining-monitor-guide). How to read the balance after a payout is in [rewards and payouts](https://iotahome.site/en/learn/erg-rewards-balances-payments).

## Common questions

### If protocol rewards use P2S, can a P2PK still receive pool ERG?

Yes. The docs say the protocol locks mining rewards in a P2S script. The 2Miners help page’s ERG payout example starts with 9, and the docs say a mainnet 9-address is always P2PK. The pool payout address and the coinbase script are not the same object.

### Can a testnet P2PK starting with 3 open the mainnet pool?

No. The docs show a testnet P2PK example starting with 3. This page looks up only a mainnet payout address that starts with 9 and checks out.

### P2SH is discussed as easier or cheaper in the docs. Will an 8-address work?

No. The docs discuss how P2SH differs from P2S and show a mainnet P2SH example starting with 8. This page’s pool-payout scope stops at mainnet P2PK. Paste a 9-address on the [ERG monitor](https://iotahome.site/en/projects/erg).

## Sources and implementation

- [Ergo Docs · Address types](https://docs.ergoplatform.com/dev/wallet/address/address_types/)
- [2Miners · ERG help](https://erg.2miners.com/help)
- [Ergo Platform](https://ergoplatform.org/)