diff --git a/plugins/soccer-scoreboard/manager.py b/plugins/soccer-scoreboard/manager.py
index 0062e9ac..0ba825cd 100644
--- a/plugins/soccer-scoreboard/manager.py
+++ b/plugins/soccer-scoreboard/manager.py
@@ -823,7 +823,16 @@ def _initialize_league_registry(self) -> None:
 
         This design allows the display logic to iterate through leagues in priority
         order without hardcoding league names throughout the codebase.
+
+        Built into a local and swapped in with a single assignment. The display
+        thread iterates ``self._league_registry`` (via
+        ``_get_enabled_leagues_for_mode``) while ``on_config_change`` rebuilds it
+        on the ConfigService-Watcher thread; mutating the live dict in place let
+        a frame observe it empty or half-populated, or raise "dictionary changed
+        size during iteration". Rebinding the attribute is atomic, so a reader
+        gets either the whole old registry or the whole new one.
         """
+        registry: Dict[str, Dict[str, Any]] = {}
         # Add predefined leagues to registry
         for league_key in PREDEFINED_LEAGUE_KEYS:
             attr_tuple = PREDEFINED_LEAGUE_ATTR_MAP.get(league_key)
@@ -831,7 +840,7 @@ def _initialize_league_registry(self) -> None:
                 continue
             live_attr, recent_attr, upcoming_attr = attr_tuple
 
-            self._league_registry[league_key] = {
+            registry[league_key] = {
                 'enabled': self.league_enabled.get(league_key, False),
                 'priority': PREDEFINED_LEAGUE_PRIORITIES.get(league_key, 99),
                 'live_priority': self.league_live_priority.get(league_key, False),
@@ -857,7 +866,7 @@ def _initialize_league_registry(self) -> None:
             recent_attr = f'custom_{safe_key}_recent'
             upcoming_attr = f'custom_{safe_key}_upcoming'
 
-            self._league_registry[league_code] = {
+            registry[league_code] = {
                 'enabled': self.league_enabled.get(league_code, False),
                 'priority': custom_priorities.get(league_code, 50),
                 'live_priority': self.league_live_priority.get(league_code, False),
@@ -869,11 +878,14 @@ def _initialize_league_registry(self) -> None:
                 }
             }
 
+        # Publish the finished registry in one atomic rebind (see docstring).
+        self._league_registry = registry
+
         # Log registry state for debugging
-        enabled_leagues = [lid for lid, data in self._league_registry.items() if data['enabled']]
-        custom_count = len([lid for lid, data in self._league_registry.items() if data.get('is_custom', False)])
+        enabled_leagues = [lid for lid, data in registry.items() if data['enabled']]
+        custom_count = len([lid for lid, data in registry.items() if data.get('is_custom', False)])
         self.logger.info(
-            f"League registry initialized: {len(self._league_registry)} league(s) registered "
+            f"League registry initialized: {len(registry)} league(s) registered "
             f"({custom_count} custom), {len(enabled_leagues)} enabled: "
             f"{[LEAGUE_NAMES.get(lid, lid) for lid in enabled_leagues]}"
         )
@@ -898,8 +910,17 @@ def _get_enabled_leagues_for_mode(self, mode_type: str) -> List[str]:
         """
         enabled_leagues = []
 
+        # One snapshot for the whole selection. _initialize_league_registry
+        # publishes a replacement registry by rebinding the attribute, so
+        # re-reading self._league_registry further down (the sort key, the debug
+        # line) could bind a NEWER registry than the one just iterated -- and a
+        # custom league collected from the old one may be absent from it, which
+        # is a KeyError in the sort. Reading once makes the whole selection
+        # consistent with a single registry.
+        registry = self._league_registry
+
         # Iterate through all registered leagues
-        for league_id, league_data in self._league_registry.items():
+        for league_id, league_data in registry.items():
             # Check if league is enabled
             if not league_data.get('enabled', False):
                 continue
@@ -924,11 +945,11 @@ def _get_enabled_leagues_for_mode(self, mode_type: str) -> List[str]:
                 enabled_leagues.append(league_id)
 
         # Sort by priority (lower number = higher priority)
-        enabled_leagues.sort(key=lambda lid: self._league_registry[lid].get('priority', 999))
+        enabled_leagues.sort(key=lambda lid: registry[lid].get('priority', 999))
 
         self.logger.debug(
             f"Enabled leagues for {mode_type} mode: {enabled_leagues} "
-            f"(priorities: {[self._league_registry[lid].get('priority') for lid in enabled_leagues]})"
+            f"(priorities: {[registry[lid].get('priority') for lid in enabled_leagues]})"
         )
 
         return enabled_leagues
@@ -990,13 +1011,17 @@ def _get_league_manager_for_mode(self, league_id: str, mode_type: str):
         The manager is retrieved from the league registry, which is populated
         during initialization. If the league or mode doesn't exist, returns None.
         """
+        # One snapshot: the membership test and the lookup must see the same
+        # registry, or a rebind between them turns the check into a KeyError.
+        registry = self._league_registry
+
         # Check if league exists in registry
-        if league_id not in self._league_registry:
+        if league_id not in registry:
             self.logger.warning(f"League {league_id} not found in registry")
             return None
 
         # Get managers dict for this league
-        managers = self._league_registry[league_id].get('managers', {})
+        managers = registry[league_id].get('managers', {})
 
         # Get the manager for this mode type
         manager = managers.get(mode_type)
@@ -1343,8 +1368,10 @@ def on_config_change(self, new_config: Dict[str, Any]) -> None:
                     thread.join(timeout=10.0)
             self._active_update_threads.clear()
 
-            # Clear stale runtime caches before rebuilding
-            self._league_registry.clear()
+            # Clear stale runtime caches before rebuilding. _league_registry is
+            # deliberately NOT cleared here: _initialize_league_registry() below
+            # rebuilds it into a local and swaps it in atomically, so the display
+            # thread never sees it empty.
             self._scroll_prepared.clear()
             self._scroll_active.clear()
             # Re-verify team codes against ESPN, so a corrected code is
diff --git a/plugins/soccer-scoreboard/manifest.json b/plugins/soccer-scoreboard/manifest.json
index 0af9ad62..fb0029c4 100644
--- a/plugins/soccer-scoreboard/manifest.json
+++ b/plugins/soccer-scoreboard/manifest.json
@@ -1,7 +1,7 @@
 {
   "id": "soccer-scoreboard",
   "name": "Soccer Scoreboard",
-  "version": "2.12.6",
+  "version": "2.12.7",
   "author": "ChuckBuilds",
   "description": "Live, recent, and upcoming soccer games across multiple leagues including Premier League, La Liga, Bundesliga, Serie A, Ligue 1, MLS, Liga Portugal, Champions League, Europa League, and FIFA World Cup",
   "category": "sports",
@@ -26,6 +26,12 @@
     "soccer_upcoming"
   ],
   "versions": [
+    {
+      "version": "2.12.7",
+      "released": "2026-08-22",
+      "ledmatrix_min_version": "2.0.0",
+      "notes": "Rebuild the league registry into a local and publish it with one atomic rebind instead of clearing the live dict and refilling it key by key. on_config_change runs on the core's config-watcher thread while the display path iterates the same registry, so saving config during a soccer frame could render a screen with no leagues, or raise \"dictionary changed size during iteration\" inside display(). Readers that consult the registry more than once (the league selection's iterate-then-sort, and the manager lookup's membership-test-then-index) now take a single snapshot, so a replacement landing mid-selection cannot turn a league collected from the old registry into a KeyError against the new one."
+    },
     {
       "version": "2.12.2",
       "released": "2026-08-19",
diff --git a/plugins/soccer-scoreboard/test_league_registry_atomic_swap.py b/plugins/soccer-scoreboard/test_league_registry_atomic_swap.py
new file mode 100644
index 00000000..5e15c3ed
--- /dev/null
+++ b/plugins/soccer-scoreboard/test_league_registry_atomic_swap.py
@@ -0,0 +1,157 @@
+#!/usr/bin/env python3
+"""
+Regression test: rebuilding the league registry must not be visible mid-flight.
+
+``on_config_change`` runs on the core's ``ConfigService-Watcher`` thread, not
+the render thread. It rebuilds the league registry, while the display path
+iterates that same dict:
+
+    _display_scroll_mode -> _get_enabled_leagues_for_mode
+        -> for league_id, league_data in self._league_registry.items()
+
+The rebuild used to clear the live dict and repopulate it key by key, so saving
+config while a soccer frame was rendering could show a frame with no leagues,
+or raise "dictionary changed size during iteration" inside display().
+
+``_initialize_league_registry`` now builds into a local and publishes it with a
+single attribute rebind, which is atomic. A reader sees either the whole old
+registry or the whole new one.
+
+Run: <core-venv>/bin/python plugins/soccer-scoreboard/test_league_registry_atomic_swap.py
+"""
+
+import sys
+import types
+from pathlib import Path
+
+plugin_dir = Path(__file__).parent
+sys.path.insert(0, str(plugin_dir))
+
+
+def _stub_core_src():
+    def mod(name, **attrs):
+        m = types.ModuleType(name)
+        for k, v in attrs.items():
+            setattr(m, k, v)
+        sys.modules.setdefault(name, m)
+        return m
+
+    mod("src")
+    mod("src.common")
+    mod("src.plugin_system")
+    mod("src.logo_downloader", LogoDownloader=object, download_missing_logo=lambda *a, **k: None)
+    mod("src.common.scroll_helper", ScrollHelper=object)
+    mod("src.plugin_system.base_plugin", BasePlugin=None, VegasDisplayMode=object)
+    mod("src.background_data_service", get_background_service=lambda *a, **k: None)
+
+
+_stub_core_src()
+
+import logging  # noqa: E402
+import inspect  # noqa: E402
+
+from manager import SoccerScoreboardPlugin  # noqa: E402
+
+results = []
+
+
+def check(case, passed):
+    results.append((case, passed))
+    print(f"  [{'pass' if passed else 'FAIL'}] {case}")
+
+
+def make_plugin():
+    p = SoccerScoreboardPlugin.__new__(SoccerScoreboardPlugin)
+    p.logger = logging.getLogger("test-soccer-registry-swap")
+    p.config = {"enabled": True, "custom_leagues": []}
+    p.display_manager = None
+    p.cache_manager = None
+    p.plugin_manager = None
+    p.league_enabled = {}
+    p.league_live_priority = {}
+    p._league_registry = {}
+    p.custom_league_map = {}
+    return p
+
+
+plugin = make_plugin()
+plugin._initialize_league_registry()
+first = plugin._league_registry
+check("registry is populated", len(first) > 0)
+
+# The old dict must survive the rebuild intact: a display thread that grabbed a
+# reference before the swap keeps iterating a complete registry.
+snapshot = plugin._league_registry
+before_len = len(snapshot)
+plugin._initialize_league_registry()
+
+check("rebuild rebinds rather than mutating in place",
+      plugin._league_registry is not snapshot)
+check("the previously-published dict is left intact",
+      len(snapshot) == before_len)
+check("new registry is complete", len(plugin._league_registry) == before_len)
+
+# Guard the mechanism itself, so a later refactor can't quietly reintroduce
+# in-place mutation of the published dict.
+src = inspect.getsource(SoccerScoreboardPlugin._initialize_league_registry)
+check("no in-place writes to the published registry",
+      "self._league_registry[" not in src)
+check("publishes with a single rebind",
+      src.count("self._league_registry = registry") == 1)
+
+occ_src = inspect.getsource(SoccerScoreboardPlugin.on_config_change)
+check("on_config_change no longer clears the live registry",
+      "self._league_registry.clear()" not in occ_src)
+
+# --- a reader must survive a replacement landing mid-selection ------------
+# _get_enabled_leagues_for_mode iterates the registry, then sorts and logs
+# using it again. If those later reads re-fetched self._league_registry, a
+# config save that drops a custom league between the iteration and the sort
+# would raise KeyError on the render thread.
+swapped = make_plugin()
+swapped._league_registry = {
+    "eng.1": {"enabled": True, "priority": 1, "is_custom": False, "managers": {}},
+    "cus.1": {"enabled": True, "priority": 2, "is_custom": True, "managers": {}},
+}
+swapped._get_league_config = lambda lid, data: {}
+
+original_items = swapped._league_registry.items
+
+
+class _SwapOnIterate(dict):
+    """Rebinds the plugin's registry the moment the selection iterates it,
+    standing in for on_config_change landing on the watcher thread."""
+
+    def items(self):
+        # The replacement no longer has the custom league.
+        swapped._league_registry = {
+            "eng.1": {"enabled": True, "priority": 1, "is_custom": False, "managers": {}},
+        }
+        return original_items()
+
+
+swapped._league_registry = _SwapOnIterate(swapped._league_registry)
+try:
+    selected = swapped._get_enabled_leagues_for_mode("live")
+    raised = None
+except KeyError as exc:
+    selected, raised = None, exc
+
+check("a registry replacement mid-selection does not raise KeyError", raised is None)
+check("the selection reflects the registry it started from",
+      selected is not None and "cus.1" in selected)
+
+# The membership test and lookup in _get_league_manager_for_mode must also
+# agree with each other.
+mgr_plugin = make_plugin()
+mgr_plugin._league_registry = {"eng.1": {"enabled": True, "managers": {"live": "M"}}}
+check("manager lookup returns from the same snapshot it tested",
+      mgr_plugin._get_league_manager_for_mode("eng.1", "live") == "M")
+
+print()
+failed = [case for case, passed in results if not passed]
+print(f"{len(results) - len(failed)}/{len(results)} passed")
+if failed:
+    for case in failed:
+        print(f"  FAILED: {case}")
+    sys.exit(1)