diff --git a/client/public/version.js b/client/public/version.js
index 95ff0d6..b5b23a4 100644
--- a/client/public/version.js
+++ b/client/public/version.js
@@ -1,5 +1,5 @@
 // Maintainer-controlled web client version.
 // Format: YYYY.MM.DD Rn (example: 2026.02.20 R2)
-window.CHGRID_WEB_VERSION = "2026.02.27 R299";
+window.CHGRID_WEB_VERSION = "2026.02.27 R300";
 // Optional display timezone for timestamps. Falls back to America/Detroit if unset/invalid.
 window.CHGRID_TIME_ZONE = "America/Detroit";
diff --git a/client/src/main.ts b/client/src/main.ts
index be78d71..9661a78 100644
--- a/client/src/main.ts
+++ b/client/src/main.ts
@@ -2825,6 +2825,11 @@ function handleAdminRolePermissionListModeInput(code: string, key: string): void
       audio.sfxUiBlip();
       return;
     }
+    if (role.name === 'admin') {
+      updateStatus('Admin role permissions are locked on.');
+      audio.sfxUiCancel();
+      return;
+    }
     const nextPermissions = new Set(role.permissions);
     if (nextPermissions.has(value)) {
       nextPermissions.delete(value);
diff --git a/server/app/auth_service.py b/server/app/auth_service.py
index e15c7d5..8e4dd15 100644
--- a/server/app/auth_service.py
+++ b/server/app/auth_service.py
@@ -307,6 +307,8 @@ class AuthService:
         """Replace one role's permission assignment with validated keys."""
 
         normalized_role = self._normalize_role_name(role_name)
+        if normalized_role == "admin":
+            raise AuthError("Admin role permissions are locked on.")
         role_row = self._db_fetchone("SELECT id, name FROM roles WHERE name = ?", (normalized_role,))
         if role_row is None:
             raise AuthError("Role not found.")
diff --git a/server/tests/test_auth_service.py b/server/tests/test_auth_service.py
index e615fbe..ee840c4 100644
--- a/server/tests/test_auth_service.py
+++ b/server/tests/test_auth_service.py
@@ -78,3 +78,12 @@ def test_delete_role_rejects_admin_and_user(tmp_path: Path) -> None:
             service.delete_role("user", "editor")
     finally:
         service.close()
+
+
+def test_update_role_permissions_rejects_admin(tmp_path: Path) -> None:
+    service = make_auth_service(tmp_path)
+    try:
+        with pytest.raises(AuthError):
+            service.update_role_permissions("admin", ["chat.send"])
+    finally:
+        service.close()