What were you trying to do that didn't work?
Do postcopy-preempt migration, when switch into postcopy-preempt stage, will hit error on the src hmp:

(qemu) migrate_start_postcopy 
(qemu) 2025-06-18T07:16:03.787576Z qemu-kvm: Unable to shutdown socket: Transport endpoint is not connected

Please provide the package NVR for which bug is seen:
hosts: kernel-5.14.0-590.el9.x86_64 and qemu-img-9.1.0-24.el9.x86_64
guest: kernel-6.12.0-80.el10.x86_64

How reproducible:
Not sure, may 1/30

Steps to reproduce
1.Boot a VM on src host, play a video on the Youtube website in VM
2.Enable postcopy-ram, postcopy-preempt capabilities both on src and dst host
3.Migrate the VM from src to dst host, during migration is active, switch to postcopy stage

Expected results
VM migration succeeds, VM works well on dst host

Actual results
When switch to postcopy stage, will get error on src hmp:

(qemu) migrate_start_postcopy 
(qemu) 2025-06-18T07:16:03.787576Z qemu-kvm: Unable to shutdown socket: Transport endpoint is not connected

Hit the different four situations when above error occurs:
1. After postcopy migration finishes, VM reboot on dst host, and finally reboot successfully, only get dst qmp info:

{"timestamp": {"seconds": 1750231021, "microseconds": 326830}, "event": "WATCHDOG", "data": {"action": "reset"}}
{"timestamp": {"seconds": 1750231021, "microseconds": 357846}, "event": "RESET", "data": {"guest": true, "reason": "guest-reset"}}
{"timestamp": {"seconds": 1750231021, "microseconds": 893184}, "event": "RTC_CHANGE", "data": {"offset": 0, "qom-path": "/machine/unattached/device[6]/rtc"}}
{"timestamp": {"seconds": 1750231047, "microseconds": 870510}, "event": "NIC_RX_FILTER_CHANGED", "data": {"name": "net0", "path": "/machine/peripheral/net0/virtio-backend"}}
{"timestamp": {"seconds": 1750231054, "microseconds": 565658}, "event": "RTC_CHANGE", "data": {"offset": 0, "qom-path": "/machine/unattached/device[6]/rtc"}}

2. After postcopy migration finishes, VM reboot on dst host, and hang in reboot stage:

3. After postcopy migration finishes, the VM connected by VNC hang, I couldn't operate the VM by the mouse. But I tried to connect the VM by 1. use telnet to connect the console; 2. use ssh to connect the VM. These two methods work, I didn't see any special errors in VM, Instead, the VM network is pretty good.

4. VM still works well on dst host after postcopy migration