VMware ESXi Host Disconnected in vCenter: How to Fix It
When an ESXi host goes Disconnected or Not Responding in vCenter, the VMs are usually still running — it's the management path that broke. Here's how to restore it without disrupting workloads.
Step 1 — Confirm it's management, not the host
A Disconnected host often still runs its VMs. First check the management network: ping the host's management IP from the vCenter server. If ping fails, the problem is network/vmk0; if ping works, the management agents are likely stuck.
Step 2 — Check the management agents
vCenter talks to the host via two daemons: hostd (host management) and vpxa (the vCenter agent). From SSH or the DCUI shell:
/etc/init.d/hostd status
/etc/init.d/vpxa statusIf either is not running or unresponsive, restart the management agents — this does not affect running VMs:
/etc/init.d/hostd restart
/etc/init.d/vpxa restart(Or use the DCUI: Troubleshooting Options > Restart Management Agents, or run services.sh restart on the host.)
Step 3 — Check for resource exhaustion
If hostd keeps dying, the host may be out of memory or its root filesystem/ramdisk is full. Check with vdf -h and esxtop; a full /var or exhausted management memory will repeatedly knock the agents over.
Step 4 — Reconnect
Once the agents are healthy and the management IP is reachable, in vCenter right-click the host → Connection > Connect. If it still won't connect, remove and re-add the host to vCenter (VMs stay running). Confirm the host's time (NTP) and certificate are valid — a large time skew also breaks the vCenter trust.
How Tech Matrix solves this in ~60 seconds
A disconnected host is stressful because you can't tell if it's the network, the agents, or the host itself — and the VMs are still running. Tech Matrix checks the management path, the hostd/vpxa state and the host's resources for you, tells you which it is, and gives the safe restart/reconnect steps for your ESXi version, with your approval.
Frequently asked questions
No. Restarting hostd and vpxa (or 'Restart Management Agents' in the DCUI) restores the management path without affecting running virtual machines.
Either the management network to vmk0 is down, or the hostd/vpxa agents are stuck or crashed — often due to a full ramdisk or memory exhaustion on the host.
Restore management reachability, restart hostd/vpxa, then right-click the host in vCenter > Connection > Connect. If needed, remove and re-add the host.