vCenter Server Appliance – Could not connect: An unknown connection error occurred

Just now and then i ran into a strange problem: my vCenter wasn’t reachable anymore.  A simple reboot works, but is no solution!

When you connect with the vSphere client you recieve the following error message:

vSphere Client could not connect to "<server ip>"
An unknown connection error occurred. (The request failed because of a connection failure"

So i tried to login into the webclient “https://<vCVA ip address>:9443” which gave me a error message:

Failed to connect to VMware Lookup Service "https://<vCVA IP address>:7444/lookupservice/sdk - SSL certificate verification failed."

So something seems to be wrong with the SSL certificate!


To resolve this issue, toggle the certificate settings:

  1. Log in the vCenter Server Appliance Web interface at “https://<vCVA ip address>:5480/“.
  2. Click the Admin tab.
  3. Regenerate certificates by selecting Toggle certificate setting. The Certificate regeneration enabled option under the Administration settings displays Yes.
  4. Reboot the vCenter Server Appliance.


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