It cannot be a “supported” configuration since ESXi 5.5 itself is no longer supported.
The same is true for ESXi 6.0 from next month.
This doesn’t necessarily mean it will work or not work, it just can’t be supported.
therefore which version is valid for complete support? 6.5?
See page 112 for Windows Server 2019: https://www.vmware.com/resources/compatibility/pdf/VMware_GOS_Compatibility_Guide.pdf
And here's the ESXi support lifecycle: https://www.vmware.com/content/dam/digitalmarketing/vmware/en/pdf/support/product-lifecycle-matrix.pdf
Many thanks! very helpful