If CNC Simulator Pro freezes on launch, closes immediately, or shows an error, work through these steps from top to bottom. Most cases are solved by updating and resetting settings.

1) Quick fixes

1. Update to the latest version, then restart Windows and try again.

2. Check requirements

   • Windows 10/11

   • .NET Framework 4.8 enabled (Windows Features)

   • Microsoft Visual C++ 2015–2022 Redistributables (both x86 and x64)

3. Antivirus

   • If your AV quarantined a file, restore/allow it and try again.

If the start screen says it can’t connect, see: “Can’t connect to the server on start‑up”.

2) Reset program settings (in‑app)

This fixes issues caused by a corrupt setting, tool library, or workpiece.

1. Double‑click the CNC Simulator Pro icon.

2. Immediately hold the left ALT key and keep holding it.

3. After a few seconds, a small window appears.

4. Click “Reset program settings (incl. tools, workpieces, etc.)”.

Heads‑up: This resets all settings and clears custom tools/workpieces. You’ll start fresh.

3) Reset from the command line (if the window never appears)

1. Press Start, type cmd, press Enter.

2. Go to the installation folder, for example:

   cd "C:\Program Files\CNCSimulator.com\CNC Simulator Pro"
   

3. Run the reset command:

   cncsimulator.exe /ds
   

4. You should see a confirmation message that defaults were restored. Start the program again.

4) If it still fails

• Reinstall cleanly
  Uninstall CNC Simulator Pro → reboot → re‑download the installer → right‑click Properties → if Unblock is shown, tick it → install → launch.

• Try on another PC
  If it works elsewhere, the issue is environmental (driver, AV, or policy) on the first machine.

• Check for crash/diagnostic files
  Open the installation folder and look for startupexception.txt or scripterrors.txt.

5) Send us details (fastest path to a fix)

Email support@cncsimulator.com with:

Subject: Simulator hangs/errors at start 
License ID: <paste from Copy to clipboard> 
CNC Simulator Pro version / Windows version: <e.g., 4.0.1.4 / Windows 11 23H2> 
What I tried: <update / reset (ALT) / reset (/ds) / reinstall / AV allow> 
Exact error text or screenshot: <paste or attach> 
Log files: <attach startupexception.txt / scripterrors.txt if present>