What happened to Sia-UI.

Sia-UI was the official desktop application for the Sia network from the project's launch in 2015 through 2024. It was a catch-all: a wallet for holding Siacoin, a renter client for buying decentralised storage, and a host client for selling storage — all in the same Electron-based application. For most of Sia's history, if you used Sia on desktop, you used Sia-UI. It was the product that most people meant when they said 'Sia wallet,' even though strictly speaking it was three products wearing one coat.

The trouble with one app for three roles is that the three roles have very different users and very different needs. A Siacoin holder wants a lightweight, secure wallet. A storage renter wants a file-management tool with contract-status UI. A storage host wants a server-operator console with uptime dashboards and billing. Sia-UI tried to be all three, and as the network matured, the seams started to show. Hosts needed server-grade tooling that fit awkwardly in a desktop GUI. Renters needed API-first interfaces that a monolithic UI couldn't cleanly expose. Wallet users had to carry the weight of renter and host code they didn't use. The long-run fix was to split.

In 2024, The Sia Foundation restructured Sia's software into three independent applications. walletd is the wallet, and only the wallet — it handles keys, signing, balance tracking, and transactions. renterd is the renter client, optimised for operating storage contracts and managing stored data at scale. hostd is the host software, built for server operators running storage capacity on the Sia network. Each is its own repository, its own release cadence, its own documentation, its own audience. The tradeoff: simpler and better-targeted tools, but a compatibility break for users who had been living inside Sia-UI. Sia-UI was marked deprecated — it would not receive v2 updates and users were directed to the new tools.

The Sia v2 hardfork activated on June 6, 2025 at block 526,000. v2 introduced Utreexo-style accumulator proofs to the consensus layer, which required changes to transaction construction and validation. Sia-UI was written against pre-v2 consensus rules and never received a v2 update — it is deprecated, by design. After June 2025, transactions constructed by Sia-UI were rejected by the network because they didn't carry the new proof structure. The v2 Final Cut cleanup fork in December 2025 at block 552,100 removed the last legacy code paths. Sia-UI, in any version, cannot transact on the post-v2 Sia network.

Your coins are fine. Siacoin isn't stored inside Sia-UI — it's stored on the Sia blockchain, and Sia-UI was just a program that could read and write to the blockchain on your behalf. Your 28 or 29-word Sia-UI seed still deterministically derives your Sia addresses; those addresses still hold whatever balance they held when you last used the wallet. What doesn't work anymore is the Sia-UI program's ability to construct valid transactions. You need a post-v2 wallet to move your coins — and before you move them, you need to migrate the legacy seed format to the new 12-word BIP39 format that post-v2 wallets use natively.

Sia Wallet v2.12.0 ships a built-in legacy seed migration assistant specifically for this situation. Install Sia Wallet, pick 'Restore or migrate' on the welcome screen, choose 'Legacy Sia-UI seed,' and enter your 28 or 29-word phrase. The assistant derives your legacy addresses, shows your current balance, generates a new 12-word seed, and walks a single on-chain transaction that moves your balance from the legacy address to the new one. The legacy seed never leaves your machine; it's held in memory only for the duration of the flow. Total time: about fifteen minutes, most of which is writing down your new seed and waiting for six confirmations. The Migration Guide covers every edge case.

For holders who migrated between the 2024 Sia-UI deprecation and the 2026 Sia Wallet launch, the options were: SiaCentral's web wallet (reliable, but browser-based and with the Chrome-flag Ledger issue); walletd directly (powerful, but developer-facing and without a built-in migration wizard); Atomic Wallet (multi-coin convenience with a 2023 security incident on record and the iOS App Store removal as a trade-off); or stay on the deprecated Sia-UI and wait (which worked until June 2025, and then didn't). Sia Wallet v2.12.0 is the first post-2024 wallet that is consumer-grade, native desktop, migration-ready, and built on upstream walletd. That's the gap the project was started to close.