It has ocurred more than once, an update is issuing these messages in a seemingly never ending stream. [https://forum.manjaro.org/t/pacman-could-not-open-file-sync-files/20046 Pacman could not open file: sync files]
这类错误已有多次发生，并在更新的过程中经久不衰。 Pacman 无法打开文件：同步文件