What happened
A wallet can hold the right keys and still miss a payment when rebuilding its records. On 2 September 2026, Bitcoin Dev Kit merged a fix for precisely that problem. BDK is a collection of software components used to build Bitcoin wallets.
The affected operation is a rescan of transactions the software already knows about. It checks which payments belong to the wallet. The old search could give different answers depending on which transaction it examined first.
What it changes
A wallet does not have just one address. It can generate a numbered sequence from the same underlying keys. BIP32 describes this arrangement, which lets a backup recover a family of keys instead of saving each one separately.
But having the recipe for addresses is different from knowing which ones received money. Software needs a stopping rule. For example, BIP44 describes searching until it encounters 20 consecutive unused receiving addresses. That is background, not the setting involved in this BDK report.
BDK's index keeps a window of addresses ready to recognise. Finding a payment further along extends that window. Previously, a payment examined before the extension could be missed for the rest of the rescan. The fix repeats the search until the window stops growing.
Think of checking envelopes against an expanding guest list. If a later envelope adds names, the earlier rejected envelopes need another look.
What it does not change
This repairs local bookkeeping. It does not rewrite Bitcoin transactions or transfer ownership of coins.
The author also identifies an adjacent limitation: incremental updates take a separate path that this patch does not repair. A complete rescan and processing a newly arrived transaction are different operations.
As checked on 9 September, this article verifies the merge, not a published wallet release containing it. The project's release page is a separate checkpoint. Wallet developers still need to establish which dependency and application versions include the change.
Context
A backup supplies the keys. Recovery software must also find the payments those keys can spend. The two jobs belong together, but success at the first does not prove success at the second. This fix addresses one concrete reason that distinction matters.