From d6ebc5a2420b7c0100cfbc77e2bb6793bff16482 Mon Sep 17 00:00:00 2001
From: Lrifton92 <Lrifton92@users.noreply.github.com>
Date: Tue, 9 Jun 2026 16:39:25 +0200
Subject: [PATCH 1/2] feature: allow custom feature bits already set by default

When a custom feature bit configured via protocol.custom-init or
protocol.custom-nodeann is already advertised in lnd's default feature
vector, newManager returned a "feature bit: X already set" error and lnd
failed to start. Re-advertising an already-set bit yields an identical
feature vector, so this is harmless.

Treat an already-set custom bit as a no-op instead of a fatal error.
Genuine conflicts between the optional and required variants of a feature
are still rejected by SafeSet.

Signed-off-by: Lrifton92 <Lrifton92@users.noreply.github.com>
---
 feature/manager.go               | 10 ++++++++--
 feature/manager_internal_test.go | 30 ++++++++++++++++++++++++++++++
 2 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/feature/manager.go b/feature/manager.go
index b1fff33c67b..9869d941a18 100644
--- a/feature/manager.go
+++ b/feature/manager.go
@@ -239,9 +239,15 @@ func newManager(cfg Config, desc setDesc) (*Manager, error) {
 					set, set.Maximum())
 			}
 
+			// If the feature bit is already advertised in lnd's
+			// default feature vector, configuring it as a custom
+			// feature produces an identical vector. Treat this as a
+			// no-op rather than failing startup (see #10883).
+			// Genuine conflicts between the optional and required
+			// variants of a feature are still caught by SafeSet
+			// below.
 			if raw.IsSet(custom) {
-				return nil, fmt.Errorf("feature bit: %v "+
-					"already set", custom)
+				continue
 			}
 
 			if err := raw.SafeSet(custom); err != nil {
diff --git a/feature/manager_internal_test.go b/feature/manager_internal_test.go
index c110fc7a9d9..fb56be157f1 100644
--- a/feature/manager_internal_test.go
+++ b/feature/manager_internal_test.go
@@ -289,3 +289,33 @@ func TestUpdateFeatureSets(t *testing.T) {
 		})
 	}
 }
+
+// TestManagerCustomFeatureAlreadyDefault asserts that configuring a custom
+// feature bit which lnd already advertises by default does not prevent the
+// feature manager from initializing. The resulting feature vector is identical,
+// so the duplicate must be treated as a no-op rather than a fatal error.
+//
+// See: https://github.com/lightningnetwork/lnd/issues/10883
+func TestManagerCustomFeatureAlreadyDefault(t *testing.T) {
+	t.Parallel()
+
+	// TLVOnionPayloadRequired is advertised by default in the Init set per
+	// testSetDesc, so configuring it as a custom feature for the same set
+	// duplicates an already-set bit. This previously failed startup with a
+	// "feature bit: ... already set" error.
+	cfg := Config{
+		CustomFeatures: map[Set][]lnwire.FeatureBit{
+			SetInit: {lnwire.TLVOnionPayloadRequired},
+		},
+	}
+
+	m, err := newManager(cfg, testSetDesc)
+	require.NoError(t, err)
+
+	// The required bit must still be advertised, and the duplicate must not
+	// have introduced its optional variant (which would form an invalid
+	// pairing). Check the exact bits via the raw vector.
+	rawInit := m.GetRaw(SetInit)
+	require.True(t, rawInit.IsSet(lnwire.TLVOnionPayloadRequired))
+	require.False(t, rawInit.IsSet(lnwire.TLVOnionPayloadOptional))
+}

From c870ccf4b5961fd2f25d8ee968b6d76c3bf94f87 Mon Sep 17 00:00:00 2001
From: Lrifton92 <Lrifton92@users.noreply.github.com>
Date: Tue, 9 Jun 2026 16:40:21 +0200
Subject: [PATCH 2/2] docs: add release note for #10888

Signed-off-by: Lrifton92 <Lrifton92@users.noreply.github.com>
---
 docs/release-notes/release-notes-0.22.0.md | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/docs/release-notes/release-notes-0.22.0.md b/docs/release-notes/release-notes-0.22.0.md
index 85626b68f41..cfaf166f2c3 100644
--- a/docs/release-notes/release-notes-0.22.0.md
+++ b/docs/release-notes/release-notes-0.22.0.md
@@ -55,6 +55,12 @@
   the reported network statistics such as total network capacity, channel
   count and max out degree.
 
+* [Fixed a bug](https://github.com/lightningnetwork/lnd/pull/10888) where
+  configuring a `protocol.custom-init` or `protocol.custom-nodeann` feature bit
+  that lnd already advertises by default caused startup to fail with a
+  `feature bit: X already set` error. Such a duplicate now yields an identical
+  feature vector and is treated as a no-op.
+
 # New Features
 
 ## Functional Enhancements
@@ -148,3 +154,4 @@
 * Boris Nagaev
 * Erick Cestari
 * Jared Tobin
+* Lrifton92