Cardano node version for mainnet and opcert issue number

Hi all,

My pool dtDn has finally been scheduled for the first time as slot leader in the following epoch and I have two questions I need to answer to make this opportunity a success.

  1. My node and relays are running version 1.34.1 . It is not clear to me if a precise date has been set to upgrade the software to 1.35.x on mainnet yet. Should I upgrade to 1.35.x for epoch 353 or should I stay in 1.34.1?

  2. I updated my kes keys twice since I started my pool meaning that the opcert issue number is now at 3. On 1.35.x the op cert counter must be exactly one more than the previously used op cert. Since I never used any op cert (my pool didn’t produce any block yet since its creation), if I am runnign 1.35, do I need to generate the kes keys using the op cert counter set to 1 or will it work with any number?
    I already asked the second question in another thread and Alexd1985 aswered that generating the kes keys with op cert counter set to 1 was not necessary. However I am not sure where he got that information and I really want to be 100% sure to not miss my first block.

Thank you in advance for any help.


I think u asked same questions days ago…

Keep 1.34.1 version and wait for 1.35.x version for new infos regarding op cert


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Hi Alex, yes I did, as I mentioned but I would like to know where to find such information (about op cert number) myself without reading the code.

What is the best channel to be informed of the time when we should deploy 1.35.x on mainnet?

On the telegram account «IOG SPO announcements» the last message we got about that subject was on July 8th and it said

«we were able to identify an issue with the recent ledger update in the Vasil hard fork release candidate, 1.35.0. It meant that when the node is running in the Babbage era and shuts down, it would need to re-sync from genesis if the snapshots are from the Babbage era.

This has now been fixed and we have tagged a release 1.35.1 which will be fully regression tested over the coming days.

If you’re currently running 1.35.0 on testnet then please upgrade to 1.35.1 as soon as you can. If you would like to upgrade to 1.35.1 on mainnet now, please feel free to do so, but please do watch out for any future releases prior to the hard fork.»

This is incredibly confusing, why would we deploy 1.35.1 on mainnet if it hasn’t been fully regression tested?
This post suggest that it is fine to run either 1.34.1 (without mentioning it) or 1.35.1 on mainnet but it is heavily subject to interpretations…
Finally the latest release on github is 1.35.0 which is the version we shouldn’t deploy on mainnet…

You will have enough time to upgrade the nodes after 1.35.x release… regarding op cert now for example if u create blocks with counter 2 with 1.34.1 or bellow u can modify/increment the counter to any value > than 2 but with 1.35.x version u will can modify/increment only to 3


Thanks for your answer, which version do you run on charity?

I agree with Alex here. Lots of time to upgrade to 1.35.x later. Keep it simple for your first block. The Vasil hard fork changes things for the kes rotation as you noted, but it hasn’t happened yet, so no panic,

Here is some more reading on the kes issue if you wanted to dig deeper, Fix kes period info command by newhoggy · Pull Request #3945 · input-output-hk/cardano-node · GitHub

And some more instructions here Adjust Node.Counter for KES - How to Guides for Coincashew Method Cardano SPOs


1.34.1 and no rush

Thank you both for your answers

When the vasil hard fork happens, it will be mandatory to run a version 1.35.x right?

What information feed do you use to know when things are supposed to happen? All the feeds I use lack clarity (or at least they lack clarity for this specific event, the vasil hard fork). As far as I know the hard fork is supposed to happen four weeks after July 3rd but since July 8th, no real news about the planning…

The information feeds I use are (may be usefull for others too)
-SPO digest from
-Telegram account IOG SPO announcements
-Telegram account Cardano Announcements
-Discord IOG’s technical community
-Notifications of new releases in cardano-node github
-Telegram account Cardano Stake Pool Best Practice Workgroup (added it right now as I edit this post and I finally found a place where people are as confused as I am regarding the planning for the hard fork :sweat_smile:)

PS: I didn’t realize that cborHex contained the certificate issue number too, thanks for the link!

For Vasil you will need to run 1.35.x.

I think on this point nobody knows when hardfork will happen. Latest info what I have that it supposed to be 3rd of July on testnet and then 4 week after on mainnet.

Thank you for your answer. I’ll put this thread as solved since I think the real issue here is that the main information source for cardano spo is a bit defective.

I agree with Alex to wait. Also we have put together a guide on how to rollback the node counter file for KES renewal after the update. Please see guide here and please share with other pools. Thanks!

Becky from IOG just posted on Discord:
“Please note that we are deprecating node versions 1.35.0 and 1.35.1 . These contain known issues and should not be used. SPOs wishing to test Vasil functions ON THE TESTNET ONLY should do so using node version 1.35.2. SPOs should continue to run 1.34.x on mainnet until an official mainnet release is confirmed.”


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