RFC: when to drop testnet3 #31975

1. 
   Sjors commented at 4:33 pm on March 3, 2025: member

   Testnet3 was deprecated in v28 with the introduction of testnet4. #31974 implements its removal.

   Dropping it in v30 seems reasonable to me, but let’s discuss this here as to not clutter the implementation PR.

   Note that v29 (coming soon), which includes testnet3, will be supported for a while. See https://bitcoincore.org/en/lifecycle/ @instagibbs wrote:

   I’ve said it elsewhere, but I think it deserves a quite long deprecation cycle, along with some data gathering.

   We don’t want services not upgrading for fixes because their test environment would break.

   e.g., what exchanges with testnet environments have adopted testnet4 (or signet), much less would be ok with removing testnet3?

   Does btcd support it? LND? Eclaire? CLN? etc.

   Lots of work to be done here imo.

2. glozow added the label Tests on Mar 3, 2025
3. glozow added the label Needs Conceptual Review on Mar 3, 2025
4. 
   fjahr commented at 8:11 pm on March 3, 2025: contributor

   I’m guessing we need to weigh the potential pain for those that have built infrastructure on Testnet3 for a while (wallets with lot’s of UTXOs for testing elaborate multisig setups, lightning nodes etc.) with the fact that Testnet3 doesn’t seem to be usable for anyone according to some commenters. It think a mailing list post is in order and if nobody complains for good reason (not “I’m rich there”) then I would even be fine with removal in v30. We can also do a Github grep and reach out to open source projects directly that still have it implemented if the ML post doesn’t seem sufficient alone.

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Sjors fjahr

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Tests Needs Conceptual Review