I made a full clone of a Windows 11 26H2 VM in VirtualBox 7.2.22 (Windows 11 25H2 host). The clone never appeared in VirtualBox Manager, and I can’t add it with Machine -> Add because its folder has no .vbox file, only disk files (2 TB split VMDK):
Windows 11 Pro 26300_9457 (Official ISO) (2026-11-11) - Fresh install Clone
Windows 11 Pro 26300_9457 (Official ISO) (2026-11-11) - Fresh install Clone-disk1.vmdk <- 0 bytes
Windows 11 Pro 26300_9457 (Official ISO) (2026-11-11) - Fresh install Clone-disk1-s001.vmdk
...
Windows 11 Pro 26300_9457 (Official ISO) (2026-11-11) - Fresh install Clone-disk1-s1025.vmdk
The 1,025 slice files add up to only about 0.3 GB, while the source VM is about 25 GB. The source VM’s hard disk is a 2 TB, dynamically allocated VMDK, split into files of less than 2 GB:
> VBoxManage showmediuminfo disk "Windows 11 Pro 26300_9457 (Official ISO) (2026-11-11b).vmdk"
Storage format: VMDK
Format variant: dynamic split2G
Capacity: 2097151 MBytes
The VBoxSVC log from the session that ran the clone (%USERPROFILE%.VirtualBoxVBoxSVC.log.*) ends with a crash on the clone thread:
00:09:53.168833 createClone !!! rtR3WinUnhandledXcptFilter caught an exception on thread 0000000000001434 in 16560 !!!
00:09:53.168865 createClone ExceptionCode=0xc0000005 ExceptionFlags=0x00000000 ExceptionAddress=00007ffdc11f23b8
00:09:53.168872 createClone ExceptionInformation[0]=0000000000000001
00:09:53.168882 createClone ExceptionInformation[1]=000001edd5533000
00:09:53.168903 createClone rax=000001edd5532fc9 rcx=000001edd5532fc9 rdx=000001edd5532f59 rbx=000001edd1e3bf98
00:09:53.168915 createClone r8 =000000000000004e r9 =0000000000000060 r10=00007ffdc11e0000 r11=00007ffdc11f23a3
[...]
00:09:53.171241 createClone 000000a11afff200: 00007ffdba219c10 - 0x00059c10 bytes into C:Program FilesOracleVirtualBoxVBoxDDU.dll
Why does cloning crash?
