vSphere (General)

Troubleshooting: Cannot Add host “Authenticity of the host’s SSL certificate is not verified”.

Troubleshooting: Cannot Add host “Authenticity of the host’s SSL certificate is not verified”.

Intro One of my customers wanted to change the hostname of the ESXi host. In this case, the ESXi hostname stayed the same, but it needed to become part of  a subdomain. Changing an ESXi hostname ...
VUM Error: Host cannot download files from VMware vSphere Update Manager patch store

VUM Error: Host cannot download files from VMware vSphere Update Manager patch store

Setup: vCSA 6.5 with embedded VUM Intro: At one of my customers, I had a weird problem that one of the hosts couldn’t updated through VUM. Time to investigate. Error: “Host cannot ...
How to Rollback an ESXi host after an update

How to Rollback an ESXi host after an update

Upgrading and updating your ESXi hosts is necessary. Updates contain bug fixes, security updates, new features or improvements, and drivers. With VUM this can be quite easy. However, sometimes you ...
vCenter doesn’t start up – Failed to start File System Check on /dev/dis..

vCenter doesn’t start up – Failed to start File System Check on /dev/dis..

A customer of mine had some problems with a vCenter (vCSA 6.5) that didn’t want to boot up anymore. First thing I checked was if I could log in on the vCenter Appliance Management Interface (VAMI). ...
vSphere Troubleshooting: Hosts Disconnects  “Agent unable to save configuration to disk: Error syncing firmware configuration: vim.fault.TooManyWrites”

vSphere Troubleshooting: Hosts Disconnects “Agent unable to save configuration to disk: Error syncing firmware configuration: vim.fault.TooManyWrites”

During a deployment of several ESXi hosts at a customer, I noticed that the new hosts were disconnecting every few minutes. When I checked the event error, it showed a lot of different errors and ...
Troubleshooting: vSphere Sessions are constantly logging off –  Connection Timeout

Troubleshooting: vSphere Sessions are constantly logging off – Connection Timeout

I recently had a problem that one of my vCenters (vCSA 6.5) was constantly logging off any kind of user after a few minutes. Which would end up with the following error output: “Your vsphere Client ...
vCSA6.5 Installation Stuck at 80% and some other fun errors during Deployment.

vCSA6.5 Installation Stuck at 80% and some other fun errors during Deployment.

if you came across this post then you’ll probably had the problem that the vCenter installation became stuck around the 80%, with the text “Installing RPM This may take several minutes”. ...
Hyper-V to VMware Conversion (V2V)

Hyper-V to VMware Conversion (V2V)

A while ago I started to make also some video’s to help people with certain problems. One of them was changing the language settings in Windows 10, but now I also made a V2V conversion ...
ESXi Install 5.x & 6.x

ESXi Install 5.x & 6.x

How to Install ESXi 5.x & 6.x The screenshots are of 5.1. but the setup is almost the same, if not the same to all versions up till 6.5. When you are installing an ESXi host, it is best to use an ...