Deprecated Features

Name	Type	First Deprecated	Last Supported	Description
listpeers.features.option_anchors_zero_fee_htlc_tx	Field	v24.08	v25.09	Renamed to `option_anchors` in the spec: check for that in `features` instead
decode.blinding	Field	v24.11	v25.05	Renamed to `first_path_key` in BOLT 4 (available in `decode` from v24.11)
onion_message_recv.blinding	Hook Field	v24.11	v25.05	Renamed to `first_path_key` in BOLT 4 (available in hook from v24.11)
decodepay	Command	v24.11	v25.12	Use `decode` which is more powerful (since v23.05)
close.tx	Field	v24.11	v25.12	Use txs array instead
close.txid	Field	v24.11	v25.12	Use txids array instead
experimental-offers	Config	v24.11	v25.05	Now the default
xpay.ignore_bolt12_mpp	Field	v25.05	v25.12	Try MPP even if the BOLT12 invoice doesn't explicitly allow it (CLN didn't until 25.02)
listpeerchannels.max_total_htlc_in_msat	Field	v25.02	v26.03	Use our_max_total_htlc_out_msat
wait.details	Field	v25.05	v26.06	Use subsystem-specific object instead
channel_state_changed.old_state.unknown	Notification Field	v25.05	v26.03	Value "unknown" is deprecated: field will be omitted instead

Inevitably there are features which need to change: either to be generalized, or removed when they can no longer be supported.

Types of deprecation:

Command: an entire command is removed. Usually replaced by a more generic or better-named one.
Config: a commandline/configuration option is removed. Usually made the default, or replaced by generalized or better-named.
Field(s): a JSON field output. We cannot detect if you are using these, of course.
Parameter(s): a JSON RPC input.
Getmanifest Reply: a field in the JSON reply which plugins give to getmanifest.
Hook Return: a field/value in the JSON reply which plugins give to a plugin hook.
Notification/Hook Field: a field in the JSON notification/hook to a plugin.

For each deprecation:

The deprecation is listed here, and in the CHANGELOG.md file.
We try to give at least 2 versions before removal.
Then one version where we issue a warning message if we detect a deprecated feature being used (not possible for deprecatred Field types).
At least one version where the deprecated feature can be explicit re-enabled using i-promise-to-fix-broken-api-user=FEATURENAME.

This is designed to minimize the chance that anyone will be surprised by a change!

You can also test earlier. Deprecated features can be disabled in three ways:

developer mode changes the default deprecations to disabled globally.
allow-deprecated-apis= lets you disable (false) or re-enable (true) globally.
The deprecations JSON API can disable/re-enable deprecations for a specific client (added in v24.02).