diff --git a/lutris/util/library_sync.py b/lutris/util/library_sync.py
index 7940cb26c..a2dbe7f3e 100644
--- a/lutris/util/library_sync.py
+++ b/lutris/util/library_sync.py
@@ -1,4 +1,5 @@
 import json
+import sys
 import time
 from typing import List, Optional
 
@@ -124,7 +125,11 @@ class LibrarySyncer:
 
     def _db_game_to_api(self, db_game):
         """Serialize DB game entry to a payload compatible with the API"""
-        categories = [self.categories[cat_id] for cat_id in self.games_categories.get(db_game["id"], [])]
+        try:
+            categories = [self.categories[cat_id] for cat_id in self.games_categories.get(db_game["id"], [])]
+        except KeyError:
+            self.panic_at_the_key_error(db_game, "id")
+            return
         return {
             "name": db_game["name"],
             "slug": db_game["slug"],
@@ -137,12 +142,23 @@ class LibrarySyncer:
             "categories": categories,
         }
 
+    def panic_at_the_key_error(self, db_game, key):
+        logger.error((("!" * 120) + "\n") * 240)
+        logger.exception("No installed_at key in db_game. CORRUPTED OBJECT!!!!!")
+        logger.exception("OBJECT CONTENT %s", db_game)
+        logger.error((("!" * 120) + "\n") * 24)
+        sys.exit(-999)
+
     def _db_games_to_api(self, db_games, since=None):
         """Serialize a collection of games to API format, optionally filtering by date"""
         payload = []
         for db_game in db_games:
             lastplayed = db_game["lastplayed"] or 0
-            installed_at = db_game["installed_at"] or 0
+            try:
+                installed_at = db_game["installed_at"] or 0
+            except KeyError:
+                self.panic_at_the_key_error(db_game, "installed_at")
+
             if since and lastplayed < since and installed_at < since:
                 continue
             payload.append(self._db_game_to_api(db_game))
diff --git a/utils/cleanup_prefix.py b/utils/cleanup_prefix.py
index cd7c2d070..40ed04c9a 100644
--- a/utils/cleanup_prefix.py
+++ b/utils/cleanup_prefix.py
@@ -113,6 +113,7 @@ def delete_known_dirs(prefix_path):
             continue
         os.remove(regfile)
 
+
 def remove_empty_dirs(dirname):
     empty_folders = []
     for root, dirs, files in os.walk(dirname, topdown=True):