Hi,
According to your description, the avhdx file and extra set of mrt rct files are possibly created because backup and replication with RCT.
(https://helpcenter.veeam.com/docs/backup/hyperv/changed_block_tracking.html?ver=100)
And you can try the following steps to check if it works:
https://blog.workinghardinit.work/2015/10/15/remove-lingering-backup-checkpoints-from-a-hyper-v-virtual-machine/
(Please note: Information posted in the given link is hosted by a third party. Microsoft does not guarantee the accuracy and effectiveness of information.)
I also find some similar problems which may be helpful for you:
https://social.technet.microsoft.com/Forums/en-US/89f62a9f-be28-4248-80c3-21d8a4d1e1d8/avhdx-leftover-from-backup-tool-how-to-merge-or-delete-those-files?forum=winserverhyperv
https://community.spiceworks.com/topic/632113-hyper-v-2012-r2-checkpoint-backups-how-to-delete?page=1
https://social.technet.microsoft.com/Forums/windows/en-US/10485462-ccdf-4ee8-8c28-5748e46ef6ce/virtual-machine-failed-to-generate-vhd-tree-catastrophic-failure0x8000ffff?forum=w8itprovirt
Thanks for your time!
Best Regards,
Mico Mi
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