diff --git a/py/lora_manager.py b/py/lora_manager.py
index 934e78b8..a8d0d8f9 100644
--- a/py/lora_manager.py
+++ b/py/lora_manager.py
@@ -23,6 +23,18 @@ logger = logging.getLogger(__name__)
 # Check if we're in standalone mode
 STANDALONE_MODE = 'nodes' not in sys.modules
 
+HEADER_SIZE_LIMIT = 16384
+
+
+def _sanitize_size_limit(value):
+    """Return a non-negative integer size for ``handler_args`` comparisons."""
+
+    try:
+        coerced = int(value)
+    except (TypeError, ValueError):
+        return 0
+    return coerced if coerced >= 0 else 0
+
 
 class _SettingsProxy:
     def __init__(self):
@@ -50,6 +62,24 @@ class LoraManager:
         """Initialize and register all routes using the new refactored architecture"""
         app = PromptServer.instance.app
 
+        # Increase allowed header sizes so browsers with large localhost cookie
+        # jars (multiple UIs on 127.0.0.1) don't trip aiohttp's 8KB default
+        # limits. Cookies for unrelated apps are still sent to the plugin and
+        # may otherwise raise LineTooLong errors when the request parser reads
+        # them. Preserve any previously configured handler arguments while
+        # ensuring our minimum sizes are applied.
+        handler_args = getattr(app, "_handler_args", {}) or {}
+        updated_handler_args = dict(handler_args)
+        updated_handler_args["max_field_size"] = max(
+            _sanitize_size_limit(handler_args.get("max_field_size", 0)),
+            HEADER_SIZE_LIMIT,
+        )
+        updated_handler_args["max_line_size"] = max(
+            _sanitize_size_limit(handler_args.get("max_line_size", 0)),
+            HEADER_SIZE_LIMIT,
+        )
+        app._handler_args = updated_handler_args
+
         # Configure aiohttp access logger to be less verbose
         logging.getLogger('aiohttp.access').setLevel(logging.WARNING)
 
diff --git a/standalone.py b/standalone.py
index 48f1a0b4..63f9b263 100644
--- a/standalone.py
+++ b/standalone.py
@@ -102,8 +102,11 @@ import asyncio
 import logging
 from aiohttp import web
 
+# Increase allowable header size to align with in-ComfyUI configuration.
+HEADER_SIZE_LIMIT = 16384
+
 # Setup logging
-logging.basicConfig(level=logging.INFO, 
+logging.basicConfig(level=logging.INFO,
                     format='%(asctime)s - %(name)s - %(levelname)s - %(message)s')
 logger = logging.getLogger("lora-manager-standalone")
 
@@ -133,7 +136,14 @@ class StandaloneServer:
     """Server implementation for standalone mode"""
     
     def __init__(self):
-        self.app = web.Application(logger=logger, middlewares=[cache_control])
+        self.app = web.Application(
+            logger=logger,
+            middlewares=[cache_control],
+            handler_args={
+                "max_field_size": HEADER_SIZE_LIMIT,
+                "max_line_size": HEADER_SIZE_LIMIT,
+            },
+        )
         self.instance = self  # Make it compatible with PromptServer.instance pattern
         
         # Ensure the app's access logger is configured to reduce verbosity
diff --git a/tests/routes/test_lora_manager_lifecycle.py b/tests/routes/test_lora_manager_lifecycle.py
index 56ebf909..1bb0f1eb 100644
--- a/tests/routes/test_lora_manager_lifecycle.py
+++ b/tests/routes/test_lora_manager_lifecycle.py
@@ -33,6 +33,7 @@ class _DummyWSManager:
 
 async def test_lora_manager_lifecycle(monkeypatch: pytest.MonkeyPatch, tmp_path: Path) -> None:
     app = web.Application()
+    app._handler_args = {"max_field_size": 1024, "foo": "bar"}
     monkeypatch.setattr(lora_manager.PromptServer, "instance", SimpleNamespace(app=app))
 
     added_static_routes: list[tuple[str, Path]] = []
@@ -174,6 +175,9 @@ async def test_lora_manager_lifecycle(monkeypatch: pytest.MonkeyPatch, tmp_path:
         lora_manager.LoraManager.add_routes()
         assert lora_manager.LoraManager._cleanup in app.on_shutdown
         assert app.on_startup, "startup hooks should be registered"
+        assert app._handler_args["max_field_size"] == lora_manager.HEADER_SIZE_LIMIT
+        assert app._handler_args["max_line_size"] == lora_manager.HEADER_SIZE_LIMIT
+        assert app._handler_args["foo"] == "bar"
         assert register_calls == [True]
         assert model_factory_calls == [app]
         assert stats_setup == [app]
diff --git a/tests/standalone/test_standalone_server.py b/tests/standalone/test_standalone_server.py
index 095cd8aa..9531bed6 100644
--- a/tests/standalone/test_standalone_server.py
+++ b/tests/standalone/test_standalone_server.py
@@ -84,6 +84,15 @@ async def test_standalone_server_sets_up_routes(tmp_path, standalone_module):
     assert server.app.on_shutdown, "shutdown callbacks must be attached"
 
 
+def test_standalone_server_raises_header_limits(standalone_module):
+    """``StandaloneServer`` configures ``handler_args`` to tolerate large headers."""
+
+    server = standalone_module.StandaloneServer()
+
+    assert server.app._handler_args["max_field_size"] == standalone_module.HEADER_SIZE_LIMIT
+    assert server.app._handler_args["max_line_size"] == standalone_module.HEADER_SIZE_LIMIT
+
+
 def test_validate_settings_warns_for_missing_model_paths(caplog, standalone_module):
     """Missing model folders trigger the configuration warning."""