Ctrl z crash 3ds max , file cant' undo and error . How to fix ctrl z not working

When you press Ctrl+Z, 3ds Max immediately displays the following error message:

“Application Error. An error has occurred and the application will now close. Do you want to attempt to save a copy of the current scene?”

After that, a backup pop-up window appears automatically. In addition, when you exit 3ds Max, even if you choose not to save the file, it is still saved automatically. This can cause many unexpected issues and inconveniences.

I have experienced this problem on two different computers, one at the office and one at home. In both cases, the issue occurred.

This error is caused by a virus called “Worm.3dmax.alc.clb”.

As a result, the Ctrl+Z (Undo) function in 3ds Max stops working properly.

Ctrl z crash 3ds max , file cant' undo and error

Empty helper nodes (e.g. “¡¡×ý×û” and “×þ×ü”).

How to fix undo errors in 3dsmax

1.For 3dsmax 2015- 2025

Close 3ds Max.
Download and install the Autodesk Security Tools.
Open your 3ds Max file again and save it.

2.For 3dsmax 2014 or lower

Open 3ds Max and go to MAXScript > Run Script.
Select the file PruneScene.mzp and click Open.
A dialog window will appear. Follow the on-screen instructions.
Click Next, then Next again to install the script.
Finally, click Run Script.

Although this is paid software, the free version can still remove this virus. Simply click the “1” button to close the window.

At this step, you can clean the file by clicking the “Start” button.

If an error occurs, you will see the following interface.

Important: At this step, click the “Protection Disabled” button to remove the virus.

You will see the following notification:“[Worm.3dmax.alc.clb] Virus detected and removed.”

Ctrl z crash 3ds max , file cant' undo and error

At the bottom of the window, you should see the message:”Success. Virutes not detected“

This undo error should now be fixed.

The 3ds Max Scene Security Tools are Autodesk’s recommended solution for detecting and removing known third-party malicious scripts, including CRPADSL, ALC, ALC2, PhysXPluginMfx, MSCPROP, and their variants.

These malicious scripts can corrupt the 3ds Max environment, cause data loss and system instability, and spread to other computers through shared 3ds Max scene files.