We are investigating fluctuating block production times, and something that caught my eyes in the logs were Collation wasn't advertised to any validator. What does this mean, exactly, and could it cause long block production times?

  • (The addition of the disputes mechanism has I believe temporarily reduced block times, but it might be fixed in v0.9.19.)
    – Squirrel
    Commented Mar 28, 2022 at 18:21
  • it looks like the para must have been assigned a core at this stage, and then the collator is issuing a discovery request to the validators associated with that core. Looking at the code the next step is moving to advance_to_advertised but it has not go that far: github.com/paritytech/polkadot/blob/…
    – Squirrel
    Commented Mar 28, 2022 at 20:23

1 Answer 1


This was partially only a logging issue, that logged this in the collator protocol in some occassions where it should not have logged the message.

The issue of fluctuating block times is a known issue and is planned to be fixed with the v0.9.19 release (at the time of writing), also see https://github.com/paritytech/polkadot/issues/4911

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