Error: "Debug tools vprobe or vprobe based packet capture is currently running on host" during NSX VIB installation or upgrade

Products

• VMware NSX

Issue/Introduction

When attempting to install or upgrade NSX VIBs on an ESXi host via SDDC Manager, NSX Manager, or vSphere Lifecycle Manager (vLCM), the process fails at the pre-check or installation stage.

Symptoms:

• Host remains in a "Pre-check Failed" or "Incomplete" state in the NSX UI.

• Error message: "Debug tools vprobe or vprobe based packet capture is currently running on host. Please disable packet capture or vprobe before upgrading"

• The pktcap-uw process may appear in the process list but cannot be terminated using standard kill signals.

Environment

 

• TCP 5.x

• NSX-T / NSX 3.x, 4.x

• ESXi 7.x, 8.x

 

Cause

The ESXi installation engine detects an active vprobe or pktcap-uw (packet capture) session. These tools attach filters to the network stack IOChain. Upgrading the NSX VIBs requires modifying these filters; if a capture is active, the modification could cause a kernel exception (PSOD). In some cases, the process may be a "zombie" process—where the tool has been closed but the kernel still holds the session handle.

Resolution

I. Identify and Terminate the Process

1. Log in to the ESXi host via SSH as root.

2. Search for active capture processes: ps -cv | grep -E "pktcap-uw|vprobe"

3. If a PID is returned, attempt to stop it: kill -9 <PID>

4. If the command returns "No such process", the process is stale and requires a management agent reset.

II. Restart Management Agents

Restarting the agents often clears the registration of stale debug sessions:

1. Place the host in Maintenance Mode (ensure VMs are evacuated).

2. Run the following commands: /etc/init.d/hostd restart /etc/init.d/vpxa restart

3. Wait 2 minutes for the agents to re-sync with vCenter/NSX Manager.

III. Final Remediation (If session persists)

If the error remains after restarting agents, a hardware reset is required to clear the kernel memory:

1. Reboot the ESXi host.

2. Once the host is back online and out of Maintenance Mode, retry the NSX VIB installation/upgrade.