1.) You have build your own package, which got another version than we have within stable or testing. Then you have to configure that within your pacman.conf to ignore that concrete package.
2.) You have different sources configured for an installation, resulting between something stable or / and testing. That would result into weird system-behaviour for sure.

To review the space on a partition: Do you need some help?

Version 0.4 only consists of core and extra. There will be no further community-repository. Just have a look here: https://www.hyperbola.info/packages/

So for sure you'll get an error 404 as there is no file to download.

ok i get that           

:: replace ca-certificates-utils with core/ca-certificates [y/n]
...
warning: tre: downgrading from version 0.8.0-4 to version 0.8.0-1 
error: failed to prepare transaction (could not find database)

if download community from 0.3.1 it installs but with"no space on device"errors, probably because my usb is 8gb?
this solved and added some error

So for sure you'll get an error 404 as there is no file to download.

pacman -Syuu
:: synchronizing package database...
core ...100%
extra ...100%
error: failed retrieving file 'community.db' from repo.hyperbola.info:50011 : the requested url returned error: 404
error: failed to update community (unexpected error)
:: starting full system upgrade...
:: replace ca-certificates-utils with core/ca-certificates [y/n]

i tried other mirrors in /etc/pacman.d/mirrorlist testing version