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How to: Upgrade to vSphere 4.1

With yesterdays release of vSphere 4.1 comes the challenge to upgrade your existing installation to this new version. Because I have been testing the beta for a while now, I couldn´t wait to try it in our new testing environment.


However, there are a few caveats:

  • VMware released a KB article with the supported upgrade methods for ESX(i) 3.0.x, 3.5 and 4 full, embedded or installable;
  • Do NOT upgrade vCenter server to version 4.1 if you are using VMware View Composer 2.0.x. Check out this VMware KB article for more information.

Before you start the upgrade process, back-up the vCenter- and Update Manager databases.

After downloading the needed ISO´s, I started with the upgrade of the vCenter server.

But first of all, I had to uninstall all incompatible vCenter components, in this case Guided Consolidation 4.0.

When this is done, it´s time to update the vCenter server.

vCenter server upgrade

Note: vCenter Server 4.1 is supported only on 64 bit operating systems. As such, there is no in-place upgrade path for vCenter Server installs on 32 bit operating systems. If your vCenter Server is installed on a 32 bit operating system, you need to switch to a new 64 bit machine where vCenter Server 4.1 can be installed. Check out this VMware KB article for an overview of the database migration procedure using the vCenter Server 4.1 migration tools.

The installation detects the earlier vCenter server installation.

The installation detects the current vCenter server database and the used ODBC driver. Check whether the correct database is displayed to avoid upgrading the incorrect database.

Confirm that you want to upgrade your existing database and that you have made a back-up before starting the upgrade process.

Specify if you want the upgrade process to upgrade your vCenter agents automatically or manually. If you want minimal disruption, choose the automatic option, although VMware HA and FT will continue to function when disconnected from the vCenter server..

Enter the password for the vCenter server service account.

Check the ports used by vCenter server. In my home test environment the changes made for the previous vCenter server installation were neatly preserved.

Then a new vCenter server installation feature. Select your vSphere setup to correctly size the memory used for the vCenter server Java Virtual Machine (JVM) memory.

There are three options, Small <100 hosts, Medium >100 hosts <400 hosts, Large > 400 hosts. Personally I think I will never use the Medium and Large option although I would love to setup such a huge environment.

When you’ve passed these 7 screens, the installation process has enough information to upgrade your previous vCenter server installation.

Next, the vSphere client upgrade.


Page 1 – vCenter server upgrade Page 2 – vSphere client upgrade Page 3 – Update Manager upgrade Page 4 –  ESX host upgrade



The founder and driving force behind VMGuru. With over 19 years experience in IT, he now works as a Cloud Management Specialist at VMware Benelux. Long time VMware VCP, VCP Desktop, VCA, VSP and VTSP and 8 year vExpert.

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  • donkarnash


    I have vcenter 4.0 update 1 with 3 hosts in cluster & HA installed on windows 2003 32bit server.

    I have to upgrade to vcenter 4.1 and installed sql express edition

    I have moved all vm's from one host to remaining other two.

    I have installed ESXi 4.1 build 260247 on one host.

    Then created a vm – windows 2008 R2 64bit – installed vcenter 4.1 & vpshere client build 258902.

    I ran the agent pre-upgrade check on the existing vcenter.

    Also ran backup.bat under datamigration on the existing vcenter.

    I copied the vcenter 4.1 installation files and datamigration folder to new server.

    I have different host name and different IP address for this new vcenter.

    I can login to the vcenter on new host but obviously it is empty.

    Now…I need some guidance here.

    I do not know if I need to migrate the existing db to new server ??

    if yes — how — what are the steps as I do not have SQL Server Management Studio on win 2003 vcenter server.

    if no — do I just run the install.bat on the new vcenter server ????

    I know I will have to update the configuration files manually as the host name and IP address are different.

    which specific files are these ????

    Can you please guide me.

    Many thanks

  • Trupel

    Thanks for the info! very helpful

  • Mr Sarge

    wy ist it necessary to install the pre-upgrade package via esxupdate before the upgrade with VUM?

  • In my opinion, migration or fresh install depends on the amount of configuration in vCenter. If you have a small scale install with a few hosts, a few resource pools, some HA and DRS config, and don't mind losing the performance history, do a fresh install. If performance history is critical and you have a large scale installation with many hosts and maybe additional tools like SRM, I would perform an upgrade.

  • Honestly? I have no idea.Maybe to fix a bug which prohibits the update with VUM but that's just speculation.

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  • John Doe

    Nice work Erik and posted just one day after 4.1 is out.
    Keep the good work.

  • Patters

    @donkarnash I had the same problem as you by the sound of it. I wrote up a workaround here:

  • Sascha Berlin/Germany

    many thanks for this how to!

    It works fine.

  • FM


    Looking at upgrading vCenter 4.0 update 1 to vCenter 4.1 and have a DSN question.

    The 4.1 upgrade guide says it needs a 64bit DSN, whilst the previous versions used a 32bit DSN.

    I created an additional 64bit DSN to point to the vCenter DB – the aiming being to get the installer to use this.

    When I run the 4.1 installation it reports I have an earlier version of vCenter alredy installed and it will upgrade this version.In the database options window it detects the 32bit DSN – so I cannot specify the 64bit DSN I created earlier. The next window has the upgrade options for the database, however I'm reluctant to continue on as it's using the 32bit DSN.

    Any advice?

  • @Home I forgot to update my DSN before the upgrade and updated my vSPhere setup without any problems. Afterwards I removed the 32 bit DSN and replaced it with a 64 bit DSN. No problem.

  • FM

    Cheers for the info.

    I shall let the installer continue with the upgrade process, and then check the DSN details.

  • thanks for this how-to! works like a charm and my (first-time) upgrade much easier!

  • Raed

    Hi All: My Name is Raed, Honestly I just finish the course for VSPHERE 4.1 installation & Implementation , Currently i am running ESXI 3.5 on 3 hosts with No VCENTER , Update Manager … ETC, Actually i am not the person who did the installation for the current 3.5 but now i want to do the upgrade for the current to 4.1, bulding a VCenter and Start enjoy using 4.1 features.

    any recommendations or guides according to what mentioned ?

    Thank you very much ….. Regards

    •  Just build a vCenter 4.1 with update manager, add the ESX3.5 host to the new vCenter server and upgrade according to the ‘how to’ above

  • Hannes

    Thanks Mate!

  • dvd zone

    I have done this

    Installed vcenter 2.5 on a host (2003 R2 32 bit, hostname vc and ipaddress Installed SQL 2005 express 2005 Management studio and took bakup of

    Then I linked it to esx1 and esx2 + san1, san2 etc. All went well

    Then I upgraded it to vcenter 4.0. All went well, I did not need to remake my datacenter and link to esx1, esx2 etc.

    Then I took a backup using datamigration tool on vcenter 4.1 dvd.

    Renamed the machined from vc to vcOLD and changed ip from to

    Installed Windows 2003 R2 64 bit, named it vc and ipaddress=

    Installed Vcenter 4.1. Then copied datamigration folder from vcOLD, ran install.bat to install update manager.

    Now I cannot see the datacenter I created or the ESX hosts anywhere.

     Am I doing anything wrong or some extra steps are needed. I also tried to install SQL 2005 express 2005 Management studio on 64 bit machine but

    “Installation of this product failed because it is not supported on this operating system.  For more information on supported configurations, see the product documentation.”

    Finally tried to restore VIM_UMDB.bak and VIM_VCDB.bak using sql express studio on vcOLD. UMDB restore went OK but the VCDB backup said

    The backup set holds a backup of a database other than the existing ‘VIM_VCDB’ database.

    Anyway the Datacenter and esx hosts are still missing.

    What is to be done?

    • When you don’t care about historic data, the fastest way to solve this is to create the datacenter add the esx hosts manualy. Because it’s only a small configuration (two hosts) this won’t be much work

  • Steve

    I just took over our vm environment at our company.  We have 4 ESX clusters plus 1 in DR.  Three of the clusters are 4.0 and one is 3.5 including the one in DR.  Now we want to upgrade our entire environment to 4.1 but I am encountering some issues.  Hoping you can help me sort it out.

    Our vcenter server is a 32bit machine and needs to be upgraded to 64bit.  The catch is that our vcenter server is a virtual machine sitting on one of the 4.0 ESX hosts.  What is your recommendation of how we should start with the upgrade process?  And do you know if our license on the vcenter server is capable of migrating to a new vcenter server or do we need a temporary license from vmware?

    Thanks Steve

  • Lorribot

    Might be me but I can never find the update files, or pretty much anything i actually want, on the VMware website, it is a complete nightmare. I wish they would sort it out or better still allow downloads to teh update manager like they do with all the other patches. Some of us have better things to do with our time than hunt around nebulous websites for patches.

  • Awesome write up! Thanks for sharing.

    • Matty