Hello,
As per the VMware Compatibility Guide, your server is supported with 6.5:
My question is before the RAM upgrade which ESXi was installed ?
And to solve this issue, i recommend to do an SPP for this server (Firmware Upgrade). For more info about SPP: Service Pack for ProLiant | Hewlett Packard Enterprise
Please consider marking this answer "CORRECT" or "Helpful" if you think your question have been answered correctly.
Cheers,
VCIX6-NV|VCP-NV|VCP-DC|
@KakHassan
linkedin.com/in/hassanalkak
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Regards,
Hassan Alkak