Problems after upgrading from 20.10

So recently, I decided to head back to Ubuntu MATE from Ubuntu, and so far pretty good.
I upgraded from 20.10 because it reached it's end of life.. but after I did that I experienced some problems.

For example, Bluetooth doesn't work (it works with Raspberry Pi OS, RetroPie, and Windows 11), but Ubuntu-based distributions fail. (It seemed to work in 20.10 however...)
Whenever I try to enable it with Bluetooth Manager, it shows up for a split second then then vanishes from the task bar.

Another problem I'm having is I can't run ubuntu-mate-welcome or Software Boutique. Whenever I tried running it through the terminal, I receive this:

[email protected]:~# ubuntu-mate-welcome --boutique
/ not root-owned 1000:1000

Linux aC-ubmPi400 5.11.0-1016-raspi #17-Ubuntu SMP PREEMPT Thu Jul 29 15:33:06 UTC 2021 aarch64 aarch64 aarch64 GNU/Linux

NAME="Ubuntu"
VERSION="21.04 (Hirsute Hippo)"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu 21.04"
VERSION_ID="21.04"
HOME_URL="https://www.ubuntu.com/"
SUPPORT_URL="https://help.ubuntu.com/"
BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/"
PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy"
VERSION_CODENAME=hirsute
UBUNTU_CODENAME=hirsute

I'm on a Raspberry Pi 400 with Ubuntu MATE 21.04 running on a 2TB HDD

Maybe try running as root?

That's what I tried to do, same error
and I don't think you're supposed to run it as root

That's very bad if the root directory / (not to be confused with root's home directory, /root), is owned by a normal user. That means that you can potentially create and delete files in the root directory, which is a security risk!

Try this:

sudo chown root: /

Do not specify the -R option unless you like borking your entire system!

By the way, while you're at it, do a:

ls -l /

...to see if there are any other obvious folders which are not owned by root. I think every one of the first-level folders in the file system should be owned by root. Certainly on my system (Debian 10, since I'm not in Ubuntu MATE at the moment), that is true:

lrwxrwxrwx   1 root root    7 Sep 17  2020 bin -> usr/bin
drwxr-xr-x   1 root root   40 Sep 21  2020 boot
drwxr-xr-x  13 root root 2840 Aug 26 19:24 dev
drwxr-xr-x   1 root root  100 Aug 26 19:17 etc
drwxr-xr-x   1 root root   60 Oct 18  2020 home
lrwxrwxrwx   1 root root    7 Sep 17  2020 lib -> usr/lib
lrwxrwxrwx   1 root root    9 Sep 17  2020 lib64 -> usr/lib64
lrwxrwxrwx   1 root root   10 Sep 17  2020 libx32 -> usr/libx32
drwx------   2 root root    3 Sep 17  2020 lost+found
drwxr-xr-x   1 root root   60 Aug 26 19:17 media
drwxr-xr-x   3 root root   29 Sep 20  2020 mnt
drwxr-xr-x   2 root root    3 Sep 17  2020 opt
dr-xr-xr-x 144 root root    0 Aug 26 19:16 proc
drwx------   6 root root  147 Oct 18  2020 root
drwxr-xr-x  18 root root  520 Aug 26 19:17 run
lrwxrwxrwx   1 root root    8 Sep 17  2020 sbin -> usr/sbin
drwxr-xr-x   2 root root    3 Sep 17  2020 srv
dr-xr-xr-x  12 root root    0 Aug 26 19:16 sys
drwxrwxrwt   1 root root  300 Aug 26 19:49 tmp
drwxr-xr-x   1 root root   60 Sep 17  2020 usr
drwxr-xr-x   1 root root  120 Sep 17  2020 var