From 37a5eee31cb71f1837a87071fcf65d614d4a2408 Mon Sep 17 00:00:00 2001
From: andrew000 <11490628+andrew000@users.noreply.github.com>
Date: Tue, 23 Dec 2025 09:50:24 +0200
Subject: [PATCH] Fix getting callback params on py3.14+

Add 1741.bugfix.rst
---
 CHANGES/1741.bugfix.rst                       |  3 ++
 aiogram/dispatcher/event/handler.py           | 31 +++++++++++++++++--
 .../test_event/test_handler.py                |  4 +--
 3 files changed, 33 insertions(+), 5 deletions(-)
 create mode 100644 CHANGES/1741.bugfix.rst

diff --git a/CHANGES/1741.bugfix.rst b/CHANGES/1741.bugfix.rst
new file mode 100644
index 00000000..5ca46ee5
--- /dev/null
+++ b/CHANGES/1741.bugfix.rst
@@ -0,0 +1,3 @@
+`inspect.getfullargspec(callback)` can't process callback if it's arguments have "ForwardRef" annotations in Py3.14+
+
+This PR replaces the old way with `inspect.signature(callback)` and add `annotation_format = annotationlib.Format.FORWARDREF` argument to it if runtime python version >=3.14.
diff --git a/aiogram/dispatcher/event/handler.py b/aiogram/dispatcher/event/handler.py
index 7aeaab96..12c41d13 100644
--- a/aiogram/dispatcher/event/handler.py
+++ b/aiogram/dispatcher/event/handler.py
@@ -1,5 +1,6 @@
 import asyncio
 import inspect
+import sys
 import warnings
 from collections.abc import Callable
 from dataclasses import dataclass, field
@@ -27,9 +28,33 @@ class CallableObject:
     def __post_init__(self) -> None:
         callback = inspect.unwrap(self.callback)
         self.awaitable = inspect.isawaitable(callback) or inspect.iscoroutinefunction(callback)
-        spec = inspect.getfullargspec(callback)
-        self.params = {*spec.args, *spec.kwonlyargs}
-        self.varkw = spec.varkw is not None
+
+        kwargs: dict[str, Any] = {}
+        if sys.version_info >= (3, 14):
+            import annotationlib
+
+            kwargs["annotation_format"] = annotationlib.Format.FORWARDREF
+
+        try:
+            signature = inspect.signature(callback, **kwargs)
+        except (ValueError, TypeError):  # pragma: no cover
+            self.params = set()
+            self.varkw = False
+            return
+
+        self.params = {
+            p.name
+            for p in signature.parameters.values()
+            if p.kind
+            in (
+                inspect.Parameter.POSITIONAL_ONLY,
+                inspect.Parameter.POSITIONAL_OR_KEYWORD,
+                inspect.Parameter.KEYWORD_ONLY,
+            )
+        }
+        self.varkw = any(
+            p.kind == inspect.Parameter.VAR_KEYWORD for p in signature.parameters.values()
+        )
 
     def _prepare_kwargs(self, kwargs: dict[str, Any]) -> dict[str, Any]:
         if self.varkw:
diff --git a/tests/test_dispatcher/test_event/test_handler.py b/tests/test_dispatcher/test_event/test_handler.py
index 1f8be4af..7105a058 100644
--- a/tests/test_dispatcher/test_event/test_handler.py
+++ b/tests/test_dispatcher/test_event/test_handler.py
@@ -57,8 +57,8 @@ class TestCallableObject:
             pytest.param(callback1, {"foo", "bar", "baz"}),
             pytest.param(callback2, {"foo", "bar", "baz"}),
             pytest.param(callback3, {"foo"}),
-            pytest.param(TestFilter(), {"self", "foo", "bar", "baz"}),
-            pytest.param(SyncCallable(), {"self", "foo", "bar", "baz"}),
+            pytest.param(TestFilter(), {"foo", "bar", "baz"}),
+            pytest.param(SyncCallable(), {"foo", "bar", "baz"}),
         ],
     )
     def test_init_args_spec(self, callback: Callable, args: Set[str]):