bitcoin-mirror/doc/release-notes-34566.md

Network changes

Custom signets now use separate data directories, with a suffix equivalent to the network magic (message start), so multiple signets can be synced. The default signet continues to use the unsuffixed directory for backward compatibility, including when the default challenge is set explicitly via -signetchallenge.

Users currently running a custom signet will have their node select a new data directory after upgrading. To avoid a resync, they should rename the existing signet directory to the new signet_XXXXXXXX format, using the getchainparams command from bitcoin-util to determine the suffix:

$ bitcoin-util -signet -signetchallenge=<challenge> getchainparams | jq -r .net.magic

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