Your cheatengine-x86_64.exe settings file (.ini or registry) might be corrupted, forcing the input box to default to "NULL."
The 100% better fix: Go to Edit -> Settings -> General Settings and click "Reset Settings."
The message is not an official, well-documented Windows or Cheat Engine error string but is commonly reported by users when the scanning process fails to read memory or when required input/options are missing or malformed. Typical underlying causes: Your cheatengine-x86_64
First, ignore the "Thread 0" part. For a regular user, that is just programmer-speak for "the first scanning process failed." The real clue is "Please fill something in." Or manually limit start/end addresses (e
Cheat Engine scans memory by comparing values. You enter a number (e.g., 100 for Ammo), and CE scans RAM to find addresses holding 100. The error occurs when Cheat Engine receives a null value or an unprocessable data type from the input box. If you still see "Scan Error: Thread 0",
Here are the four real reasons this happens:
00400000 – 7FFFFFFF).If you still see "Scan Error: Thread 0", the game process likely has kernel-level hooks blocking CE. In that case, consider using Cheat Engine Lite or a Kernel-mode bypass (advanced, not covered here).
Still stuck? Provide the exact game name and Cheat Engine version in a comment for a targeted fix.