<div>
What version is your vCenter?<br />
Only vcenter 5.5 can manage ESXi 5.5. vCenter 5.0 will not be able to manage 5.5 ESXi host.<br />
<br />
You will have to either upgrade the vCenter to 5.5 or downgrade the host to 5.0.<br />
<br />
If the version compatibilty is taken care of then you can take a look at this KB Article<br />
<a href="http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=2009217" rel="ugc nofollow">http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=2009217</a>
</div>


<div>
It's vCenter v 5.0. &nbsp;If I upgrade this will I still be able to manage the 5.0 version of ESX that's on the existing hosts?
</div>


<div>
<div class="content wysiwyg-content">
I'm have a ESX 5.0 cluster running with vCenter. &nbsp;I'm trying to add a 5.5 host to the datacentre, not cluster. &nbsp;However I get the follow message<br />
<br />
A general system error occurred: &nbsp;Timed waiting for vpxa to start<br />
<br />
There was some license alert when trying to add about features not working with this version. &nbsp;Should this work or do I have to upgrade the 5.0 version first?
</div>
</div>


I'm have a ESX 5.0 cluster running with vCenter.  I'm trying to add a 5.5 host to the datacentre, not cluster.  However I get the follow message

A general system error occurred:  Timed waiting for vpxa to start

There was some license alert when trying to add about features not working with this version.  Should this work or do I have to upgrade the 5.0 version first?

Adding a esx 5.5 host to a 5.0 cluster

VMware, a software company founded in 1998,  was one of the first commercially successful companies to offer x86 virtualization. The storage company EMC purchased VMware in 1994. Dell Technologies acquired EMC in 2016. VMware’s parent company is now Dell Technologies.

VMware has many software products that run on desktops, Microsoft Windows, Linux, and macOS, which allows the virtualizing of the x86 architecture.  Its enterprise software hypervisor for servers, VMware vSphere Hypervisor (ESXi), is a bare-metal hypervisor that runs directly on the server hardware and does not require an additional underlying operating system.