Are you still running ESXi 6.0? 
The End of General Support for vSphere 6.0 is March 12, 2020. To maintain your full level of Support and Subscription Services, VMware recommends upgrading to vSphere 6.5 or vSphere 6.7.
 
https://kb.vmware.com/s/article/66977

What does End of General Support mean? 
General Support is what you use to get support from VMware. When General Support ends, the product moves into Technical Guidance support.
Technical Guidance is primarily available via the self-help portal, telephone support is no longer available. Support requests can still be raised however support is limited. Critically, no bug fixes, security patches or updates are released while in the Technical Guidance phase. 

Which products are affected?
This includes the following releases:

• vCenter Server 6.0
• vCenter Update Manager 6.0
• ESXi 6.0
• Site Recovery Manager 6.0 and 6.1
• vSAN 6.0, 6.1 and 6.2
• vSphere Data Protection 6.0 and 6.1
• vSphere Replication 6.0 and 6.1

Do you need help upgrading?
Whether you have a plan, need help creating a plan, need help implementing a plan or just want to discuss the options available to you, Workspace IT can help.