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Chapter 10 · The 2026 chain split, in one page

The 2026 Bitcoin Chain Split, Explained for Families (Do This, Not That)

Prefer to watch? This chapter is also a short video (about 4½ minutes). The full text is below.

This chapter is dated on purpose. It describes events up to October 2026; check bitcoinfamilyvault.com for anything newer.

In one minute: On August 8, 2026, a small group of bitcoin users broke away and started a separate chain. It shares bitcoin's history up to that day, so if you held bitcoin in your own wallet before then, the same keys now control coins on both chains. Your bitcoin on the main chain, the one every major exchange and wallet calls bitcoin, is fine. The one thing to avoid: don't try to claim, sell or move the breakaway coins. Transactions can be copied from one chain to the other, so moving one can move the other. And anyone who asks for your words to "claim" them is a thief.

What happened

Bitcoin runs on rules that every participant's software checks. In 2026, some users wanted a temporary new rule, called BIP-110, that would limit non-financial data, like images, stored on bitcoin's blockchain. ¹

Almost nobody mining bitcoin adopted it: in the last period before the deadline, about 2.5% of blocks signaled support. ¹ On August 8, 2026, at block 961,632, the software enforcing the new rule rejected a block the rest of the network accepted, and its users split off onto their own chain. ¹

That breakaway chain struggled: it produced just two blocks in its first eight hours. ² On August 30 it changed how it's mined to a different method called BLAKE2b, making it a separate coin, sometimes listed as BTCB2. ³⁴ As of late September, a few small exchanges traded it; no major exchange listed it. ⁴

The main chain carried on as if nothing had happened.

Why your coins may exist twice

Think of the blockchain as a ledger book. On August 8, someone photocopied the whole book and started writing in the copy. Every entry up to that day is in both books.

So if you held bitcoin in your own wallet before August 8, your keys control those coins in both books: real bitcoin on the main chain, and the same amount of the breakaway coin on the other. Nothing you need to do to "get" them; nothing you need to do to keep your real bitcoin safe.

The one thing to avoid

Don't try to claim, sell or move the breakaway coins.

The two chains still accept the same transactions unless a special signing option is used, and ordinary wallets don't use it. ²³ So a transaction you make on one chain can be copied onto the other. Try to sell the breakaway coins, and the buyer can copy that same transaction onto the main chain and take your real bitcoin. ² Ledger warned its customers not to claim or move the fork's coins for exactly this reason. ⁵

And remember Rule #1. If you held bitcoin in your own wallet before the split, the breakaway coins are already yours, under your existing keys. There is no "claim" step. Any website, app, email or helpful stranger offering to claim, redeem or unlock them for you, in exchange for your words, is a thief. ⁴⁶

As one guide put it: "If in doubt, do nothing. Waiting costs you nothing." ⁶

If you, or a helper, run your own bitcoin software

Most families use the app from their device's maker, which follows the main chain. But if you run your own bitcoin "node" software at home, check that it follows the main chain: some 2026 versions of one popular node program follow the breakaway chain instead. ³ Your recovery drill from Chapter 6 won't catch this, because your first address is the same on both chains. Ask your helper to confirm which chain your software is on.

Talk about it

1. Did we hold bitcoin in our own wallet before August 8, 2026?
2. If someone offered to help us "claim" free coins, what would we do?
3. Do we run any bitcoin software ourselves, and does it follow the main chain?

For almost every family, the right answer to the split is: do nothing, and don't let anyone talk you into doing something.

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