diff --git a/main.py b/main.py
index a6fdaf43c..7b45b0f1f 100644
--- a/main.py
+++ b/main.py
@@ -147,7 +147,16 @@ def execute_prestartup_script():
             spec.loader.exec_module(module)
             return True
         except Exception as e:
+            import traceback
             logging.error(f"Failed to execute startup-script: {script_path} / {e}")
+            from nodes import record_node_startup_error
+            record_node_startup_error(
+                module_path=os.path.dirname(script_path),
+                source="custom_node",
+                phase="prestartup",
+                error=e,
+                tb=traceback.format_exc(),
+            )
         return False
 
     node_paths = folder_paths.get_folder_paths("custom_nodes")
diff --git a/nodes.py b/nodes.py
index 2b63f9fbb..7dfe78954 100644
--- a/nodes.py
+++ b/nodes.py
@@ -2152,6 +2152,78 @@ EXTENSION_WEB_DIRS = {}
 # Dictionary of successfully loaded module names and associated directories.
 LOADED_MODULE_DIRS = {}
 
+# Mapping from internal module_parent values to the public "source"
+# category the API exposes. Keeps the on-disk layout decoupled from
+# the names the frontend/Manager switches on.
+_NODE_SOURCE_BY_PARENT = {
+    "custom_nodes": "custom_node",
+    "comfy_extras": "comfy_extra",
+    "comfy_api_nodes": "api_node",
+}
+
+
+def _node_source_from_parent(module_parent: str) -> str:
+    return _NODE_SOURCE_BY_PARENT.get(module_parent, "custom_node")
+
+
+# Dictionary of custom node startup errors, keyed by "<source>:<module_name>"
+# so that name collisions across custom_nodes / comfy_extras / comfy_api_nodes
+# do not overwrite each other. Each value contains: source, module_name,
+# module_path, error, traceback, phase.
+NODE_STARTUP_ERRORS: dict[str, dict] = {}
+
+
+def _read_pyproject_metadata(module_path: str) -> dict | None:
+    """Best-effort extraction of node-pack identity from pyproject.toml.
+
+    Returns a dict with the Comfy Registry-style identity (pack_id,
+    display_name, publisher_id, version, repository) when the module
+    directory contains a pyproject.toml. Returns None when no toml is
+    present or parsing fails for any reason — startup-error tracking
+    must never itself raise.
+    """
+    if not module_path or not os.path.isdir(module_path):
+        return None
+    toml_path = os.path.join(module_path, "pyproject.toml")
+    if not os.path.isfile(toml_path):
+        return None
+    try:
+        from comfy_config import config_parser
+
+        cfg = config_parser.extract_node_configuration(module_path)
+        if cfg is None:
+            return None
+        meta = {
+            "pack_id": cfg.project.name or None,
+            "display_name": cfg.tool_comfy.display_name or None,
+            "publisher_id": cfg.tool_comfy.publisher_id or None,
+            "version": cfg.project.version or None,
+            "repository": cfg.project.urls.repository or None,
+        }
+        # Drop empty fields so the API payload stays compact.
+        return {k: v for k, v in meta.items() if v}
+    except Exception:
+        return None
+
+
+def record_node_startup_error(
+    *, module_path: str, source: str, phase: str, error: BaseException, tb: str
+) -> None:
+    """Record a startup error for a node module so it can be exposed via the API."""
+    module_name = get_module_name(module_path)
+    entry = {
+        "source": source,
+        "module_name": module_name,
+        "module_path": module_path,
+        "error": str(error),
+        "traceback": tb,
+        "phase": phase,
+    }
+    pyproject = _read_pyproject_metadata(module_path)
+    if pyproject:
+        entry["pyproject"] = pyproject
+    NODE_STARTUP_ERRORS[f"{source}:{module_name}"] = entry
+
 
 def get_module_name(module_path: str) -> str:
     """
@@ -2261,14 +2333,30 @@ async def load_custom_node(module_path: str, ignore=set(), module_parent="custom
                         NODE_DISPLAY_NAME_MAPPINGS[schema.node_id] = schema.display_name
                 return True
             except Exception as e:
+                tb = traceback.format_exc()
                 logging.warning(f"Error while calling comfy_entrypoint in {module_path}: {e}")
+                record_node_startup_error(
+                    module_path=module_path,
+                    source=_node_source_from_parent(module_parent),
+                    phase="entrypoint",
+                    error=e,
+                    tb=tb,
+                )
                 return False
         else:
             logging.warning(f"Skip {module_path} module for custom nodes due to the lack of NODE_CLASS_MAPPINGS or comfy_entrypoint (need one).")
             return False
     except Exception as e:
-        logging.warning(traceback.format_exc())
+        tb = traceback.format_exc()
+        logging.warning(tb)
         logging.warning(f"Cannot import {module_path} module for custom nodes: {e}")
+        record_node_startup_error(
+            module_path=module_path,
+            source=_node_source_from_parent(module_parent),
+            phase="import",
+            error=e,
+            tb=tb,
+        )
         return False
 
 async def init_external_custom_nodes():
diff --git a/server.py b/server.py
index 2f3b438bb..50d35dd25 100644
--- a/server.py
+++ b/server.py
@@ -763,6 +763,23 @@ class PromptServer():
                 out[node_class] = node_info(node_class)
             return web.json_response(out)
 
+        @routes.get("/custom_node_startup_errors")
+        async def get_custom_node_startup_errors(request):
+            # Group errors by source ("custom_node" / "comfy_extra" / "api_node")
+            # so the frontend/Manager can render them in distinct sections.
+            # `module_path` is stripped because the absolute on-disk path is
+            # internal detail that the frontend has no use for.
+            grouped: dict[str, dict[str, dict]] = {
+                "custom_node": {},
+                "comfy_extra": {},
+                "api_node": {},
+            }
+            for entry in nodes.NODE_STARTUP_ERRORS.values():
+                source = entry.get("source", "custom_node")
+                public_entry = {k: v for k, v in entry.items() if k != "module_path"}
+                grouped.setdefault(source, {})[entry["module_name"]] = public_entry
+            return web.json_response(grouped)
+
         @routes.get("/api/jobs")
         async def get_jobs(request):
             """List all jobs with filtering, sorting, and pagination.
diff --git a/tests-unit/node_startup_errors_test.py b/tests-unit/node_startup_errors_test.py
new file mode 100644
index 000000000..533ba78e7
--- /dev/null
+++ b/tests-unit/node_startup_errors_test.py
@@ -0,0 +1,145 @@
+"""Tests for the custom node startup error tracking introduced for
+Comfy-Org/ComfyUI-Launcher#303.
+
+Covers:
+- load_custom_node populates NODE_STARTUP_ERRORS with the correct source
+  for each module_parent (custom_nodes / comfy_extras / comfy_api_nodes).
+- Composite keying prevents collisions between modules with the same name
+  in different sources.
+- record_node_startup_error stores the expected fields.
+"""
+import textwrap
+
+import pytest
+
+import nodes
+
+
+@pytest.fixture(autouse=True)
+def _clear_startup_errors():
+    nodes.NODE_STARTUP_ERRORS.clear()
+    yield
+    nodes.NODE_STARTUP_ERRORS.clear()
+
+
+def _write_broken_module(tmp_path, name: str) -> str:
+    path = tmp_path / f"{name}.py"
+    path.write_text(textwrap.dedent("""\
+        # Deliberately broken module to exercise startup-error tracking.
+        raise RuntimeError("boom from " + __name__)
+    """))
+    return str(path)
+
+
+def test_record_node_startup_error_fields(tmp_path):
+    err = ValueError("kaboom")
+    nodes.record_node_startup_error(
+        module_path=str(tmp_path / "my_pack"),
+        source="custom_node",
+        phase="import",
+        error=err,
+        tb="traceback-text",
+    )
+    assert "custom_node:my_pack" in nodes.NODE_STARTUP_ERRORS
+    entry = nodes.NODE_STARTUP_ERRORS["custom_node:my_pack"]
+    assert entry["source"] == "custom_node"
+    assert entry["module_name"] == "my_pack"
+    assert entry["phase"] == "import"
+    assert entry["error"] == "kaboom"
+    assert entry["traceback"] == "traceback-text"
+    assert entry["module_path"].endswith("my_pack")
+
+
+@pytest.mark.asyncio
+@pytest.mark.parametrize(
+    "module_parent,expected_source",
+    [
+        ("custom_nodes", "custom_node"),
+        ("comfy_extras", "comfy_extra"),
+        ("comfy_api_nodes", "api_node"),
+    ],
+)
+async def test_load_custom_node_records_source(tmp_path, module_parent, expected_source):
+    module_path = _write_broken_module(tmp_path, "broken_pack")
+
+    success = await nodes.load_custom_node(module_path, module_parent=module_parent)
+    assert success is False
+
+    key = f"{expected_source}:broken_pack"
+    assert key in nodes.NODE_STARTUP_ERRORS, nodes.NODE_STARTUP_ERRORS
+    entry = nodes.NODE_STARTUP_ERRORS[key]
+    assert entry["source"] == expected_source
+    assert entry["module_name"] == "broken_pack"
+    assert entry["phase"] == "import"
+    assert "boom from" in entry["error"]
+    assert "RuntimeError" in entry["traceback"]
+
+
+@pytest.mark.asyncio
+async def test_load_custom_node_collision_across_sources(tmp_path):
+    # Same module name registered as both a custom_node and a comfy_extra;
+    # composite keying should keep both entries.
+    cn_dir = tmp_path / "cn"
+    extras_dir = tmp_path / "extras"
+    cn_dir.mkdir()
+    extras_dir.mkdir()
+    cn_path = _write_broken_module(cn_dir, "nodes_audio")
+    extras_path = _write_broken_module(extras_dir, "nodes_audio")
+
+    assert await nodes.load_custom_node(cn_path, module_parent="custom_nodes") is False
+    assert await nodes.load_custom_node(extras_path, module_parent="comfy_extras") is False
+
+    assert "custom_node:nodes_audio" in nodes.NODE_STARTUP_ERRORS
+    assert "comfy_extra:nodes_audio" in nodes.NODE_STARTUP_ERRORS
+    assert (
+        nodes.NODE_STARTUP_ERRORS["custom_node:nodes_audio"]["module_path"]
+        != nodes.NODE_STARTUP_ERRORS["comfy_extra:nodes_audio"]["module_path"]
+    )
+
+
+@pytest.mark.asyncio
+async def test_load_custom_node_attaches_pyproject_metadata(tmp_path):
+    pack_dir = tmp_path / "MyCoolPack"
+    pack_dir.mkdir()
+    (pack_dir / "__init__.py").write_text("raise RuntimeError('boom')\n")
+    (pack_dir / "pyproject.toml").write_text(textwrap.dedent("""\
+        [project]
+        name = "comfyui-mycoolpack"
+        version = "1.2.3"
+
+        [project.urls]
+        Repository = "https://github.com/example/comfyui-mycoolpack"
+
+        [tool.comfy]
+        PublisherId = "example"
+        DisplayName = "My Cool Pack"
+    """))
+
+    success = await nodes.load_custom_node(str(pack_dir), module_parent="custom_nodes")
+    assert success is False
+
+    entry = nodes.NODE_STARTUP_ERRORS["custom_node:MyCoolPack"]
+    assert "pyproject" in entry, entry
+    py = entry["pyproject"]
+    assert py["pack_id"] == "comfyui-mycoolpack"
+    assert py["display_name"] == "My Cool Pack"
+    assert py["publisher_id"] == "example"
+    assert py["version"] == "1.2.3"
+    assert py["repository"] == "https://github.com/example/comfyui-mycoolpack"
+
+
+@pytest.mark.asyncio
+async def test_load_custom_node_no_pyproject_skips_metadata(tmp_path):
+    # Single-file extras-style module: no pyproject.toml exists alongside it,
+    # so the entry must not contain a 'pyproject' key.
+    module_path = _write_broken_module(tmp_path, "lonely")
+    assert await nodes.load_custom_node(module_path, module_parent="comfy_extras") is False
+    entry = nodes.NODE_STARTUP_ERRORS["comfy_extra:lonely"]
+    assert "pyproject" not in entry
+
+
+def test_unknown_module_parent_defaults_to_custom_node():
+    assert nodes._node_source_from_parent("custom_nodes") == "custom_node"
+    assert nodes._node_source_from_parent("comfy_extras") == "comfy_extra"
+    assert nodes._node_source_from_parent("comfy_api_nodes") == "api_node"
+    assert nodes._node_source_from_parent("something_else") == "custom_node"