Activation Phase

Work : Maintainers, Auditors, Miners

Once broad consensus has been established, the BIPs are written, the tests are complete, and the code has been merged, it’s time for activation. Provided all the previous steps were taken, this can be the easiest part of the process.

There are two approaches that can be taken here:

• Expedited activation
  • An expedited activation becomes active in a short timeframe, despite the risk of significant proportion of validating nodes not updating to support the new rules.
  • This is made safer by requiring near unanimous enforcement of the new rules by miners.
  • As such, expedited activations are triggered after 90% of hashpower signals activation readiness, and then occurs automatically after some pre-determined delay.
  • If there was not a true consensus for adoption of the change, this approach has a chance to detect that when miner signalling fails to achieve the 90% threshold.
• Flag day activation
  • A flag day activation by contrast is simply scheduled to occur automatically at a time well in the future.
  • This time must be chosen to be sure that almost all node operators will have upgraded to new versions of their node software that enforce the new rules.
  • This does not rely on miner support or signalling.
  • If there was not a true consensus for adoption of the change, this approach does not provide a way to detect that failure other than via a potential chainsplit (either as part of activation via mandatory signalling, or post-activation via an attempt to violate the new rules).

Provided the previous phases were all followed in good faith, both approaches are likely to work without any problems. The approach recommended here is as follows:

• Talk to miners, make sure they’re not opposed
• If they are opposed, evaluate their reasons:
  • If there is widespread opposition, determine why you mistakenly thought there was consensus for the proposed change, and return to earlier phases.
  • If the proposal is known to be distinctly bad for miners, but there is widespread consensus for it to be activated anyway, continue anyway, on the basis that a long-term benefit for Bitcoin is also a long-term benefit for miners.
• Attempt an expedited activation with a high threshold (90% or 95%) and a short window (two or three months).
• If expedited activation fails, and there is still widespread consensus that the change is desirable, do a flag day activation.