Dear Cobo users,

To provide a better transaction experience, a new Reorg transaction status will soon be introduced for MPC Wallets.

What is Reorg?
Reorg stands for reorganization. In blockchain, a Reorg occurs when two or more blocks are mined at the same time and then added to the blockchain, creating a fork. When one side of the fork exceeds the length of the other, the shorter side will be discarded and the longer side will become the main chain. This process is known as reorganization. During the reorganization process, transactions on the discarded side may be rolled back.

At what stage of the transaction does the Reorg status occur?
Once a transaction has at least one confirmation on the blockchain, a reorganization may occur. In Cobo's transaction status system, it corresponds to the following stages:

• WaaS 1.0 API: A Reorg can occur after the status [PENDING_CONFIRMATION (501)] has appeared, but before the required number of confirmations on-chain is reached.

• WaaS 2.0 API: A Reorg can occur after the status [CONFIRMING (confirmations(1/m))] has appeared, but before the required number of confirmations on-chain is reached.

What are the impacts of the Reorg status?

If you are using the WaaS 1.0 API
Affected wallet types:

• MPC Send/Receive Wallets

• MPC Web3 Wallets 

For deposit transactions:
1. A new transaction status, Reorg (902), will be added. This status indicates that the transaction has failed and is in a final state. A callback message will be sent for this status.
2. After the transaction is broadcasted on-chain, Cobo will create a new transaction and push a callback message for the new transaction.

If you are using the WaaS 2.0 API
Affected wallets types:

• MPC Wallets (Organization-Controlled)

• MPC Wallets (User-Controlled)

For deposit transactions:
Under the Failed transaction status, a Reorg sub-status will be added, and a webhook event will be triggered for this status.

Specific adaptation process
Adaptation is only required for deposit transactions.

If you are using the WaaS 1.0 API:

• (Recommended) If you record the deposit amount when the transaction reaches the “SUCCESS” status, no extra adaptation is needed.

• If, due to business needs, you record the deposit amount when the transaction reaches the “PENDING_CONFIRMATION(501)” status, and a reorganization occurs for that transaction, Cobo will send a callback message with the Reorg status. At that point, you need to:

1. Discard the deposit record.
2. Once the transaction is re-broadcasted on-chain, Cobo will create a new transaction and notify you of the new transaction with callback messages. You can record the new deposit amount accordingly.

If you are using the WaaS 2.0 API:

• (Recommended) If you record the deposit amount when the transaction reaches the “Completed” status, no extra adaptation is needed.

• If, due to business needs, you record the deposit amount when the transaction reaches the “Confirming” status, and a reorganization occurs for that transaction, the transaction status will become “Failed (Reorg)” and Cobo will send you a webhook event. At that point, you need to:

1. Discard the deposit record.
2. Once the transaction is re-broadcasted on-chain, Cobo will create a new transaction and notify you of the new transaction with a webhook event. You can record the new deposit amount accordingly.

Expected release dates:

• Development environment: October 28th.

• Production environment: November 18th.

To avoid any disruption to your business operations, please complete the necessary adaptations before Cobo releases this new status. Should you have any questions, feel free to contact us.

Cobo Support
October 21, 2024