The simulator hangs or shows an error at start — what should I do?

Modified on Sat, 18 Oct at 4:59 AM

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.

To start, CNC Simulator Pro needs to contact our licensing server over the internet using standard HTTP communication on port 80. This connection verifies your license before the simulator opens. The process is automatic and normally completes within a second or two, after which your license details appear in the program.

0) Quick connectivity check (recommended first)

Open Command Prompt (press Start → type cmd → Enter) and run this command to verify that your PC can reach our license web service:

curl -sS -X POST "https://cncsimulator.com/CNCSimServerWebServiceP.asmx/GetFreeVersionWebPage" ^  -H "Content-Type: application/x-www-form-urlencoded" --data ""

Expected: a short XML line that looks like this:
<string xmlns="http://www.cncsimulator.com/webservices">http://…/Download.html</string>

If you see a long “Just a moment…” HTML page, or any error/timeout, your network or security software is blocking the request. Please send us a screenshot of the full output.

1) Quick fixes

Update to the latest version, then restart Windows and try again.
Requirements
- Windows 10/11
- .NET Framework 4.8 enabled (Windows Features)
- Microsoft Visual C++ 2015–2022 Redistributables (both x86 and x64)
Antivirus
- If your AV quarantined a file, restore/allow it and try again.
- If the start screen says it can’t connect, see the connectivity check above.

2) Reset program settings (in-app)

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

Double-click the CNC Simulator Pro icon.
Immediately hold the Left ALT key and keep holding it.
After a few seconds, a small window appears.
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)

Press Start, type cmd, and press Enter.

Go to the installation folder, for example:

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

Run the reset command:
```
cncsimulator.exe /ds
```
You should see a confirmation that defaults were restored. Start the program again.

4) Optional: Run our License Diagnostic Tool

If the app still will not start, please download and run our diagnostic tool. It reproduces the license checks and saves an encrypted log we can analyze.

Get the CNC Simulator License Diagnostic Tool

5) Reinstall cleanly (if needed)

Uninstall CNC Simulator Pro.
Reboot Windows.
Re-download the installer.
Right-click the installer → Properties → if “Unblock” is shown, tick it.
Install and launch.

6) Try on another PC

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

7) Check for crash/diagnostic files

Open the installation folder and look for startupexception.txt or scripterrors.txt. Include them when you contact us.

8) Contact us — info to include for fastest help

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 / curl test / diagnostic tool
Exact error text or screenshot
Log files: attach startupexception.txt / scripterrors.txt (if present)
Connectivity test output: copy the entire curl result from step 0
Your public IP address (both IPv4 and IPv6 if available)

How to find your public IP(s)

You can use either method and paste the result:

Open a browser and visit whatismyip.com or ifconfig.me.

Or in Command Promptrun:

:: IPv4 
curl -s https://ipv4.icanhazip.com 

:: IPv6 (if your network supports IPv6) 
curl -s https://ipv6.icanhazip.com