The Tezos Docs say:

Any node running the May release, in case of a successful promotion vote, will activate protocol 005_PsBABY5H, which contains a bug affecting bigmaps in smart contracts.

We advise users to update to this release so that the corrected protocol 005_PsBabyM1 will be activated.

How does the network decide which is the “right” protocol?

  • 2
    and even if they force code software to use another proto, they'll also be subject to accusation of doubles on the "correct fork. (correct being the one the natural protocol chose)
    – Bo Byrd
    Commented Oct 13, 2019 at 17:10

2 Answers 2


What happen at the network level is the combination of 2 phenomenons:

  • First and foremost, we can expect that bakers (who voted for this amended protocol!) will run up to date software and therefore produce blocks in protocol PsBabyM1 so very few blocks in protocol PsBABY5Hwill ever be produced.

  • Second, even if there is people with baking rights who produce blocks in PsBABY5H, up to date nodes will hamper there propagation. Indeed, as it has been added in the code of tezos-node that instead of activating PsBABY5H, PsBabyM1 should be activated, up to date nodes will accept and broadcast to their peers blocks they receive made in protocol PsBabyM1 but reject and discard prospective blocks made in protocol PsBABY5H.


Once a baker activates the BABYM1 protocol, BABY5 blocks are considered invalid. Once a baker activates the BABY5 protocol, BABYM1 blocks are considered invalid. There is no competition in this case and thus no decision has to be made regarding which protocol is the right one.

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