I will add a comment to the original bug  to see of the changes can be integrated into Proxmox, so we could avoid needing the script to replace the Proxmox-provided nsupdate script with the modified one after Proxmox updates.
Hi, I have not (knowingly) removed anything under /etc/kernel/postinst.d/*, but there is nothing there regarding initramfs-tools:
# ls /etc/kernel/postinst.d/*
I do have initramfs-tools installed as pero dpkg output...
I am experiencing the same issue since approximately September 2022 or so (can't recall exactly). I have checked my system and I do *not* have the file /proxmox_install_mode.
In my case, the latest kernel where this happened is pve-kernel-5.15.83-1-pve. Following the troubleshooting asked...
I have attached the scripts here. I had to add ".txt" at the end so they could be uploaded.
dns_nsupdate.sh.modified is located in /usr/share/proxmox-acme/dnsapi/
check_dns_nsupdate.sh is located in /root/, and is invoked every night via cron, with an entry like the following one:
00 10 * * *...
Basically, I followed the instructions set put here 
I will paste or attach the script itself and the crontab as soon as I can extract them, so they can also be found here.
@TonyArr, last time I tried this following suggestions from the comments on the forum it did not work for me with the scripts included with proxmox. So I used a different script that replaces the one provided by Proxmox, which works for me. I have a cron job that warns me if the script changes...
i am trying to use LetsEncrypt certificates using Acme in Proxmox 6.2 with the new DNS verification. Specifically, I am trying to use nsupdate.
Following the instructions in  and the information in , I have created a new ACME challenge configuration in my Datacenter...