Unable to Connect to External Renderer

If you attempt to send a model to KeyShot using the ZBrush to KeyShot Bridge and receive the error:

"Unable to Connect to External Renderer"

this indicates that ZBrush was unable to establish communication with KeyShot.

There are several possible causes.

1. Live Linking Not Enabled in KeyShot

KeyShot must have Live Linking enabled in order to receive data from ZBrush.

To verify:

1. Launch KeyShot.

2. Open Edit > Preferences.

3. Locate the Live Linking option.

4. Ensure that Live Linking is enabled.

The exact location of this option may vary slightly depending on your KeyShot version.

After enabling Live Linking, restart both KeyShot and ZBrush and try again.

2. KeyShot Not Fully Launched

If you attempt to send a model before KeyShot has completely finished launching, the connection may fail.

Make sure KeyShot is fully open and responsive before sending the model again from ZBrush.

3. Antivirus or Security Software Interference

The most common cause of this issue is antivirus or endpoint security software interfering with installation or communication.

Security software can:

• Block required background services
• Prevent file creation
• Interfere with network-based communication between ZBrush and KeyShot

If you suspect antivirus interference:

1. Uninstall ZBrush completely.

2. Delete any remaining ZBrush installation folders.

3. Temporarily disable all antivirus software, including Windows Defender.

4. Reinstall ZBrush.

5. Add both ZBrush and KeyShot installation directories to your antivirus whitelist before re-enabling protection.

Then test the connection again.

Additional Notes

• Ensure both ZBrush and KeyShot are installed for the same user account.
• Ensure both applications are running with the same privilege level (both normal user or both Run as Administrator).
• Make sure your KeyShot license is active and functioning properly.

If the issue persists, please include your ZBrush version, KeyShot version, and operating system when contacting support.