So recently I have had an issue with dpkg, and when using apt/apt-get, I would get an error about 50unattended-upgrades.ucftmp.
I've looked around the communities, and nobody had a specific answer. Yes, you might say that there are plenty of answers, but note that the file extension is .ucftmp. Literally, there are NO questions/answers with that extension. 50unattended-upgrades has many questions, but not with the extension.
The issue started a while ago when I tried to install something with apt, and it gave the whole "dpkg/lock" thing so I went to delete it because I wasn't using anything besides the command I was using. But I missed the last 5 characters in sudo rm /var/lib/dpkg/lock, and deleted the dpkg folder. I was able to find an answer that worked, and I used that and left it (if you want that question I can find it, so just let me know).
Just today, I was having issue with RAM, and I needed to install the memtest86+ package, and I was having the issue with 50unattended-upgrades, and also it would say that there was issues with the unattended packages, samba packages, and a few others.
Here is what happens when I try to install memtest86+ (it was already installed but the output still is an issue):
scoutchorton@scoutcbuntu-pc:~$ sudo apt install memtest86+ Reading package lists... Done Building dependency tree Reading state information... Done memtest86+ is already the newest version (5.01-3ubuntu2). The following package was automatically installed and is no longer required: mokutil Use 'sudo apt autoremove' to remove it. 0 upgraded, 0 newly installed, 0 to remove and 249 not upgraded. N: Ignoring file '50unattended-upgrades.ucftmp' in directory '/etc/apt/apt.conf.d/' as it has an invalid filename extension
Unable to use any package stuff, and it is super annoying.