Where does one get the basic .*-config.json, .*-topology.json and .*-genesis.json files for package building nowadays? The URLs that always worked for me seem down, e.g.:


This makes it quite hard to rebuild this package that depends on the configs. Somewhere on the interwebs they mention a switch from hydra.iohk.io to cache.iog.io, but nope, that doesn’t work either. (Or perhaps the URL structure is completely different.)

I could probably just reuse the files from 1.35.3 for 1.35.4, but (sort of) dislike the idea; I like to keep things clean & correct & buildable long-term.

So what’s the issue here? Is it just temporary downtime? Has there been a change in the config file provisioning? Or have the config files themselves been replaced? (If so, is there a migration guide?) Looking at the 1.35.4 release notes, I can’t spot any news concerning the .json files.

1 Answer 1


The hydra.iohk.io site went through unexpected retirement (and may not be restored). But the release notes for 1.35.4 already have updated links for binary download (which points to update-cardano-mainnet.iohk.io) and configs (which points to https://book.world.dev.cardano.org/environments.html).

Also, the config files you download from that site are available on github here

  • 1
    Well, the cardano-world repo doesn’t have tags, but I assume that the 1.35.4-node-bump branch might do. 🤪 In retrospect, the reason why my vigorous GitHub searches found nothing was … the renaming of mainnet-config.json to config.json. That’s a level of encryption that my brain just could not penetrate. Dec 5, 2022 at 21:32

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