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BIP 91 activation. What are the possible scenarios?

20 July 2017 21:00, UTC

According to BitcoinMagazine.com, this night, July 21, 2017, over 90 percent of bitcoin hash rate signaled support for BIP 91.

BIP 91 activation means that miners have support UASF protocol or a soft fork. It will lead to a further activation of Segregated Witness or SegWit. Besides it means that the potential Bitcoin chain split in two which was expected on August 1 will not happen. However, practically it is not that easy.

BIP 91 activation meant that most of miners would signal at a particular time which option they support by switching on bit 4. It happened on the night of July 21, 2017.

The second stage of BIP 91 support means that during two weeks 95 percent of miners have to use the first signal bit - bit 1 by embedding it in the blocks they mine. Up to now this threshold has not yet been met and less than 50 percent of miners did this.

If all goes well and most of miners support BIP 91, their computing power should control the longest valid chain according to all Bitcoin nodes. This chain, in its turn, will consist of blocks bit 1 SegWit-signaling blocks only, which activates in this way. Correspondingly, UASF activation will take place in mid-August followed by SegWit activation - two weeks later.

If it doesn’t go well, and miners refuse to include BIP 1 in their blocks, UAHF (hard fork) scenario will work and Bitcoin will split.