It's been a month since I upgraded my Arch Linux desktop. Today, I tried to update my Arch Linux system, and ran into an error that said "error: failed to commit transaction (conflicting files) stfl: /usr/lib/libstfl.so.0 exists in filesystem". It looks like one library (/usr/lib/libstfl.so.0) that exists on my filesystem and pacman can't upgrade it. If you're encountered with the same error, here is a quick fix to resolve it.
Solve "error: failed to commit transaction (conflicting files)" In Arch Linux
You have three options.
1. Simply ignore the problematic stfl library from being upgraded and try to update the system again. Refer this guide to know how to ignore package from being upgraded.
2. Overwrite the package using command:
$ sudo pacman -Syu --overwrite /usr/lib/libstfl.so.0
3. Remove stfl library file manually and try to upgrade the system again. Please make sure the intended package is not a dependency to any important package. And also check the archlinux.org there are mentions of this conflict.
$ sudo rm /usr/lib/libstfl.so.0
Now, try to update the system:
$ sudo pacman -Syu
I chose the third option and just deleted the file and upgraded my Arch Linux system. It worked just fine!