From 70d8a536f1c0eb965c2fa52076532fe52f08ef60 Mon Sep 17 00:00:00 2001
From: James Swartz <jameseraleswartz@gmail.com>
Date: Fri, 18 Sep 2026 14:14:25 -0400
Subject: [PATCH] Fix Kitty crashing on startup when disk is full

---
 kitty/boss.py   |  3 ++-
 kitty/config.py | 23 +++++++++++++++--------
 2 files changed, 17 insertions(+), 9 deletions(-)

diff --git a/kitty/boss.py b/kitty/boss.py
index 7228de459..d4e1f5eba 100644
--- a/kitty/boss.py
+++ b/kitty/boss.py
@@ -463,7 +463,8 @@ class Boss:
         set_boss(self)
         self.mappings: Mappings = Mappings(global_shortcuts, self.refresh_active_tab_bar)
         self.notification_manager: NotificationManager = NotificationManager(debug=self.args.debug_keyboard or self.args.debug_rendering)
-        self.atexit.unlink(store_effective_config())
+        if effective_config_path := store_effective_config():
+            self.atexit.unlink(effective_config_path)
 
     def startup_first_child(self, os_window_id: int | None, startup_sessions: Iterable[Session] = ()) -> None:
         si = startup_sessions or create_sessions(get_options(), self.args, default_session=get_options().startup_session)
diff --git a/kitty/config.py b/kitty/config.py
index d18325b5d..58ea0648a 100644
--- a/kitty/config.py
+++ b/kitty/config.py
@@ -207,14 +207,21 @@ def store_effective_config() -> str:
     import stat
     import tempfile
 
-    dest = os.path.join(cache_dir(), 'effective-config')
-    os.makedirs(dest, exist_ok=True)
-    raw = '\n'.join(effective_config_lines)
-    with suppress(FileNotFoundError), tempfile.NamedTemporaryFile('w', dir=dest) as tf:
-        os.chmod(tf.name, stat.S_IRUSR | stat.S_IWUSR)
-        print(raw, file=tf)
-        path = os.path.join(dest, f'{os.getpid()}')
-        os.replace(tf.name, path)
+    path = ''
+    try:
+        dest = os.path.join(cache_dir(), 'effective-config')
+        os.makedirs(dest, exist_ok=True)
+        raw = '\n'.join(effective_config_lines)
+        with suppress(FileNotFoundError), tempfile.NamedTemporaryFile('w', dir=dest) as tf:
+            os.chmod(tf.name, stat.S_IRUSR | stat.S_IWUSR)
+            print(raw, file=tf)
+            path = os.path.join(dest, f'{os.getpid()}')
+            os.replace(tf.name, path)
+    except OSError as err:
+        # writing the effective config is a best effort debugging aid, do not
+        # let it prevent kitty from starting, for example, when the disk is full
+        log_error(f'Failed to store effective config with error: {err}')
+        path = ''
     return path