Before each update, check Archlinux news, there may be special instructions.
When updating you system with
# pacman -Syu you may sometimes encounter this error:
error: could not prepare transaction
pacman has detected a file conflict, and is preventing you to overwrite those files. So it's user responsability to take a decision.
To solve this you have to check that those files are not used by any installed package with the command:
$ pacman -Qo /absolut/file/path.
If no package is using the file you will get this normal error:
$ pacman -Qo /absolut/file/path
Now you can rename the file (
mv /path/file.ext /path/file.ext.bck), then try the update again
# pacman -Syu and then remove the, now, useless file (
But if the file is used report a bug.