Error when trying to update

[linux-aarhus]

We have now confirmed the metadata stored in /var/lib/pacman/local is corrupt.

To be able to fix file system errors you will your rescue stick - that is the stick, where you have either prepared for the situation or the stick from which you installed Manjaro.

Your forum account goes back 5 years but in any case see

[root tip] [recovery] Basic Manjaro Linux Rescue and Recovery

Purpose It is not intended as a one-stop-solution guide. The intention is To Provide A Basic Understanding of the steps required to succesfully recover when an incident has prevented the operating system from loading. Requirements Basic understanding of using a console or virtual terminal to execute commands. Ability to edit configuration files using terminal a console editor like nano, micro or vi(m). You are willing to learn The knowledge gained and skills acquired will be applicable - n…

When have boot your system using the rescue stick - you can proceed to check the file system on your root partition

From your inxi

@Momotaros

Partition: 
  ID-1: / size: 95.92 GiB used: 30.8 GiB (32.1%) fs: ext4 dev: /dev/sda1 
  ID-2: /boot/efi size: 500 MiB used: 312 KiB (0.1%) fs: vfat dev: /dev/sda3 
  ID-3: /home size: 818.86 GiB used: 468.9 GiB (57.3%) fs: ext4 
    dev: /dev/sda2 

Open a terminal and enter

sudo su

Then run a check on the partition (the -y argument will attempt repair errors on the fly)

fsck.ext4 /dev/sda1 -y