An app developer can change a feature, publish a new version and ask users to install it. But Bitcoin, a form of digital currency, has no equivalent update button. Its software runs across thousands of independently operated computers, and the people maintaining those decentralized systems do not always agree on what should change.
While the price of each unit of bitcoin remains closely watched, a new rule can suddenly affect wallets, miners, exchanges and users across the network. Developers can propose and test code, but whether it becomes part of the Bitcoin network depends on the individuals who choose to run a particular update.
No company controls the release
Bitcoin is open-source software, so anyone can inspect the code or suggest a change. Bitcoin Core developers maintain its most widely used features, but they do not control every computer connected to the network. A wallet provider, mining company or individual node operator can delay an update, reject it or use a different proposed change. Many of these changes begin as Bitcoin Improvement Proposals, or BIPs. These documents set out the technical details and give developers a common place to discuss possible effects. Some proposals remain under debate for years, while others reach Bitcoin Core without being widely adopted.
There are practical reasons for moving slowly. A flawed change could introduce a security weakness or leave different groups following incompatible transaction rules. Disagreements can also concern fees, data use and whether a claimed improvement is worth changing established behavior. That makes Bitcoin different from a product created and maintained by one company. A software team can decide when an app changes and which version users receive. But Bitcoin develops through a looser process in which technical work and voluntary adoption happen separately.
Taproot took years to reach the network
Taproot is the clearest recent example of a long-term and wide-scale change. According to a Binance Academy explanation of Taproot, the upgrade combined three Bitcoin Improvement Proposals covering Schnorr signatures, Taproot and Tapscript. Bitcoin Core developer Greg Maxwell first proposed the idea in January 2018. The code was merged into Bitcoin Core in October 2020 and activated on November 14, 2021, meaning nearly four years passed between the first proposal and activation.
More than 90% of miners supported the upgrade before it went live, Binance Academy reported. That level of support suggested that most block producers were ready to apply the new rules, reducing the chance of an immediate split. Taproot was designed as a soft fork, allowing older software to continue recognizing blocks created under the updated rules. Compatibility made the change easier to introduce than an incompatible hard fork, but it did not make the process quick. Developers still spent years discussing the design, checking the code and working out how activation should happen. Nothing installed itself across the network — each participant decided whether and when to upgrade.
Quantum research creates a new test
Taproot shows how long a planned, compatible update can take. That slow process has become more relevant as researchers study whether future quantum computers could undermine the cryptography used to protect Bitcoin transactions. On March 31, 2026, Google Research reported that a sufficiently advanced machine might break the relevant form of elliptic-curve cryptography using fewer than 500,000 physical qubits. Google reported that was about 20 times fewer than an earlier estimate. Building a reliable machine at that scale is unattainable using current systems.
A recent Brown lecture offered a similarly measured perspective on quantum computing. California Institute of Technology Professor of Chemistry Garnet Chan argued that classical computers still outperform quantum machines in many practical chemistry problems. The lecture was not about Bitcoin, but it highlighted the distance between theoretical capabilities and machines researchers can use today. That distance gives Bitcoin developers time, though not an unlimited amount. A post-quantum migration would require agreement on a replacement before a capable machine appeared.
Depending on the address type, a Bitcoin public key — a code that allows you to participate in transactions — may already be visible or may be revealed when funds are spent. A powerful enough quantum computer could theoretically use that information to derive the corresponding private key, which would give them total control over your funds. Reuters reported that one recent estimate placed roughly 35% of circulating bitcoin in addresses whose public keys may already be exposed. Estimates differ and no current machine can steal those coins, but the figure provides a possibility of how many addresses might eventually need attention.
Releasing code would be only the beginning
Identifying a replacement signature system, in which a piece of data proves that a transaction is properly authorized, would not settle the issue. Developers would have to test how the new system affects transaction size, network capacity and wallet compatibility. Many post-quantum signatures are larger than those Bitcoin uses now, so the choice could increase the amount of data attached to each transaction. Older wallets would create another problem. Active users could move funds into new address formats, but coins in abandoned wallets or accounts with lost keys might remain where they were. No administrator could simply set a deadline and transfer them automatically.
Wallet companies would need time to add the new addresses. Users would then decide whether to move their funds, while miners and node operators consider whether to accept the rules. Even people who agreed that quantum resistance was necessary could disagree over the technical method or the treatment of older coins. Taproot proved that Bitcoin can change, but it also showed that publishing code is only one part of the process. A future post-quantum upgrade would succeed only after enough independent participants chose to use it.