• vSphere vCenter Server is inaccessible through browser client with errors such as "503 not available".
• Check of services through the vSphere Appliance Management Interface (VAMI, via https://vcenter_ip_or_fqdn:5480) show vmware-vpxd and other required services not running
• A reboot of vCenter Server doesn't resolve the issue.

• Services vpxd depends on are not starting
• Disk space is full
• Database problems
• Operating System problems
• System performance/system resource problems

Determine whether Services vpxd depends on are not starting

vCenter Server 7.0 vpxd service dependencies:

1. rhttpproxy and vmware-vpostgres need to start.
   • If not started, then lookupsvc cannot start.
   • vpxd-svcs and vmware-vpxd also depend on vmware-vpostgres.
2. lookupsvc needs to start
   • If not started, then vpxd-svcs cannot start.
   • vmware-vpxd also depends on lookupsvc.
3. vpxd-svcs needs to start.

Determine whether disk space is full

• In Appliance: Follow vCenter Server Appliance disk space is full to find out if disk space is full, and if so, how to resolve this.
• In Windows: Follow The VMware VirtualCenter Server service does not start due to insufficient disk space

Determine whether the problem is due to database problems

1. Look for any entries containing "error vpxd" and "SQL".

• In Appliance, run this command to list the vmware-vpxd service logs entries related to SQL errors:

• In Windows versions, this is located in: C:\ProgramData\VMware\vCenter Server\logs\vmware-vpx

2. Further, look at the PostgreSQL logs.

• In Appliance versions, this is located in: /var/log/vmware/vpostgres.
• In Windows versions, this is located in: C:\ProgramData\VMware\vCenter Server\logs\vpostgres.

3. Troubleshoot the issue based on error or message:

• In Windows versions, There can be other unique complications. See Troubleshooting vpxd service on Windows vCenter Server.
• In Appliance, you can validate the database, and even set this to be done on a schedule. See Validate the Consistency of the vCenter Server Appliance 6.5 and Newer Databases.

Operating System problems

• In Appliance: Check whether vCenter Server Appliance vpxd.cfg is valid

System performance problems/System resource problems

• Detecting high storage communication latency: 

1. Find out which ESXi host is managing the vCenter virtual machine.
2. Connect as the root user to this ESXi host command line by console or via SSH client
3. Run the command to check for very high latency:

cat /var/log/vmkernel.log |grep "I/O latency increased" |awk '$20 >= 80000' |less

If you see very high latency, see the " performance has deteriorated" message in ESXi for more information.

• Detecting snapshot disks

If your vCenter Server has snapshot virtual disks running on it, if there are a large number of them, or if they have grown large, it can also cause a performance impact which will cause vpxd to stop running.

Snapshots might exist which are don't show up in the vCenter or ESXi GUI

1. Directly examine the files in the vCenter Server directory to ensure there aren't snapshots on the VM

Snapshot files will generally look like vmname-00000x.vmdk, where vmname is the name of the vCenter VM, and the x is the number of the snapshot.
Example: myvcenter-000001.vmdk
It is highly recommended to never keep a snapshot running on a VM for more than 3 days.

2. Consolidate the vCenter VM.

• Detecting other performance or resource problems:

  • In Appliance: You can run the command vimtop to see the performance statistics of the VM.
  • In Windows: You can see performance under Task Manager > Performance.

For either Appliance or Windows vCenter Servers, you can look at the virtual machines' performance history for CPU. storage, memory, and networking in the ESXi or vCenter host clients.

If there are any errors regarding resources in logs, or if the performance monitors show resources being pegged, this is suspicious for a performance or resource problem.

• vpxd service may be shut down by the operating system under some conditions to prevent database corruption. Change those advanced settings at your own risk.
• vCenter/vpxd being down does NOT stop currently running ESXi hosts or VMs from running. There are some management tasks that can still be run from ESXi host clients.
• vpxd service being down does mean the vCenter cannot manage the VMs or ESXi hosts, and other processes which depend on the vCenter Server such as Horizon View VDI deployments, backups that use vCenter, and more.
• Always ensure you have a good backup of the vCenter, and take a snapshot of the vCenter VM (when possible) before making any configuration changes.