It is an existing limitation in design of netdump.
When PSOD happens in DF/NMI/MCE contexts, netdump cannot work even though it has be configured. The warning message logged on PSOD screen:
"Cannot continue NetDump from DF/NMI/MCE stack."
And then coredump switches to disk/file dump automatically. If no disk/file dump configured, user may see more warning messages:
"No place on disk to dump data."
"No file configured to dump data."
VMware vSphere ESXi 8.0.x
VMware vSphere ESXi 7.0.x
VMware vSphere ESXi 6.5
VMware vSphere ESXi 6.7
This is by design
Use local disk dump or file dump.