Introducing Enhanced Bitcoin Transaction Reliability with BitGo’s New Unspent Selection Improvements

At BitGo, we’re committed to delivering a streamlined and efficient experience for clients building and approving multiple transactions. A key part of that commitment is constantly refining our technology to solve real problems our clients face. Today, we’re excited to share an update that makes transaction building more seamless and error-free: our improved Unspent Selection process.

The Transaction Challenge

For anyone managing digital asset transactions, building and approving multiple transactions at once has historically posed a challenge. Here’s why: each transaction requires a unique set of “inputs” (unspent funds) to be selected. If multiple transactions use the same inputs and are sent for approval simultaneously, errors can occur due to unintentional double spending. This issue is especially prevalent when transactions are queued up for approvals, requiring careful tracking to avoid conflicts.

In the previous setup, when a transaction was created and entered the approval queue, the inputs in that transaction were not set aside, leaving them eligible to be selected in a new transaction. This could lead to double-spend errors and costly delays, as the conflicting transactions would have to be modified or rebuilt.

The Solution: Smarter Unspent Selection

Our new Unspent Selection update directly addresses this problem by automatically excluding inputs used in pending approvals from the selection process for new transactions. This means that when you initiate a new transaction, the system automatically knows to skip over inputs that are already awaiting approval in another transaction.

This new feature offers two key benefits for our clients:

1. Immediate Error Detection
   Double-spend errors are now caught at the very start of the transaction creation process rather than post-approval. This enhancement saves valuable time and ensures your workflow isn’t interrupted by preventable errors during transaction approvals.

2. Enhanced Multi-Transaction Efficiency
   Clients can now build and approve multiple transactions at once, confident that each transaction is using unique inputs. This improvement eliminates the need for manual input selection oversight and supports a faster, smoother approval process.

How It Works: A Quick Overview

Here’s how this improvement changes the process:

• When you build a transaction and send it for approval, the inputs used are flagged and automatically excluded from being selected in any subsequent transaction.

• If another transaction requires the same input while it’s in a pending approval status, the system will automatically identify it and prevent the conflict, ensuring a seamless transaction experience.

• This process is entirely automated, so you can create and approve transactions faster and more confidently than ever.

Frequently Asked Questions

Why does my spendable balance decrease by the entire input amount, even for smaller transactions?
Bitcoin transactions require the full input amount to be used, with the remaining funds returned as “change.” For example, if you send 1 BTC from a 10 BTC input, your spendable balance temporarily decreases by 10 BTC, not just 1 BTC.

Are inputs excluded in pending approval the same as reserved unspents?
Inputs flagged in pending approvals are indeed excluded, but they are not marked as “reserved.” Only reserved or frozen unspents have a formal reserved status.

How can I release inputs excluded due to a pending approval?
To release these inputs, simply cancel the pending approval associated with them.

Why might I see a “not enough funds” error when approving a transaction?
This could happen if network fee rates increased since the transaction was created. Our system attempts to adjust the unspents if this happens, but if there aren’t enough funds to cover the new fee, approval may still fail.

Can I see which unspents are used in each pending approval?
Currently, you can view this information through our API/SDK/Express. While this feature isn’t available in the UI just yet, let us know if that visibility would be useful for your team!

Better Performance, Better Experience

With this new update, BitGo continues to enhance the reliability, flexibility, and efficiency of your transaction process. By eliminating double-spend errors and supporting concurrent transaction management, we’re focused on making your transaction workflows faster and more effective.

Have Questions?

If you have any inquiries or need assistance, don't hesitate to reach out by emailing support@bitgo.com.