Shaolinfry Proposes BIP 148 User Activated Soft Fork

On March 20, 2017, pseudonymous Bitcoin developer Shaolinfry published Bitcoin Improvement Proposal 148 (BIP 148), which outlined a radical approach to activate Segregated Witness through what became known as a User Activated Soft Fork (UASF). The proposal suggested that if miners failed to signal support for SegWit by a certain date, users running BIP 148-compatible software would reject blocks from non-signaling miners, effectively forcing SegWit activation through user consensus rather than miner consensus.

This represented a direct challenge to the notion that miners controlled Bitcoin's technical direction and introduced a new dynamic into the scaling debate.

BIP 148 was controversial and potentially risky because it could cause a chain split if significant economic actors (exchanges, merchants, wallet providers) and users adopted it while miners did not. If this occurred, there would be two versions of Bitcoin—one with SegWit activated following BIP 148 rules, and one following the existing protocol without SegWit.

The proposal was motivated by frustration with miners' apparent reluctance to activate SegWit despite the solution being ready and tested. SegWit required 95% of miner signaling to activate through the original BIP 9 mechanism, and some believed miners were strategically blocking activation to extract concessions. BIP 148 proposed changing the activation to August 1, 2017, giving the community several months to coordinate.The proposal energized SegWit supporters and created significant uncertainty about Bitcoin's future, as it raised the possibility of a contentious fork that could split the network and ecosystem.