[Guide-Server Virtualization] Update VMware ESXi 4.1 to Update 1- VMKernel Release Build 348481

Update VMware ESXi 4.1 to Update 1

Server virtualization software VMware ESXi is the best choice for learning purpose at your home or office. It can be installed in normal computer with VMware workstation or directly on physical computer, more over, it’s a free product. Recently VMware released Update 1 for ESX, ESXi and vSphere products, which is covered in this post.  This small guide shows how to update VMware ESXi 4.1 to update 1 (VMKernel Release Build 348481)

Update 1 is an important update and its having several fixes, new guest OS support with updated VMware tools update. More information about update 1 is available here.

I’m doing this in my testing server virtualization environment which is installed in VMware workstation in Windows 7 PC. The update can be done easily by installing VMware vCLI in a Windows host which can communicate to ESXi server then download the update from official site and push the updates from Windows 7 host.

See Also,

How to install VMware ESXi on VMware workstation.

How to connect FreeNAS iSCSI disks to VMware ESXi

Simple Steps in Updating VMware ESXi 4.1 to Update 1

1) Download here and install VMware vCLI in Windows 7 computer.

Update VMware ESXi 4.1 to Update 1

This will install some scripts and folders inside,

C:\Program Files\VMware\VMware vSphere CLI folder.

2) Download appropriate update version from official site here.

Update VMware ESXi 4.1 to Update 1

Download the first update. It’s a .zip file. You don’t need to unzip this file.


3) To make the update command easy, I suggest to move the downloaded zip file to following location in your Windows host.

C:\Program Files\VMware\VMware vSphere CLI\bin

4) Make sure Windows host is communicating to VMware ESXi Server ( just do a network ping).

Pause or shutdown all virtual machines/servers running in ESXi host and put server to ‘Maintenance Mode’


5) Go to C:\Program Files\VMware\VMware vSphere CLI\bin and run following command to view the update name and Bulletin ID.

perl vihostupdate.pl --server [hostip] --username root --password password -b [update-file-name] -l

Here is the example of command for my setup.


The above command communicate with server against available updates and list out the Bulletin ID and summary.

6) Now we need to update each package with following command.

perl vihostupdate.pl --server [hostip] –-username root --password password -i -b [update-file-name] -B [Bulletin ID]

Here is the example of update command for my setup.


Do not restart the host now, repeat the same steps for each bulletin ID. Restart the host after all bulletin updates are done.

Also in vSphere client, you can see some activity during the installation of updates.


After successfully installed the all updates with bulletin IDs, restart the VMware ESXi host server.

7) Now, connect the host through VMware vSphere client utility. It may request to update the vSphere client to 4.1 update 1.

Here is the download link

Exit the maintenance mode and start the virtual machines. You can check the current version of VMware ESXi server now.

After update

after_update 4.1_update1

Before Update


8.) If the update 1 is causing any issues, then you can roll back to earlier version. ( I did these steps inside VMware workstation, so snapshot will be helpful for me)

More information about rolling back VMware ESXi server to previous version- check this guide. This is the original source for this my guide.

Share your issues and successful update attempts by this method.

Dinesh is the founder of Sysprobs and written more than 400 articles. Enthusiast in Microsoft and cloud technologies with more than 15 years of IT experience.

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