Parece que é o mysql.service que erros em você loggs cerca de 10 min após o início.
Aug 29 18:17:12 flippingbits com.canonical.Unity.Scope.Academic.Zotero[1788]: local variable 'backup_dbFile' referenced before assignment
Aug 29 18:17:12 flippingbits com.canonical.Unity.Scope.Info.Calculator[1788]: Operation:
Aug 29 18:22:06 flippingbits systemd[1]: mysql.service start-post operation timed out. Stopping.
Aug 29 18:22:06 flippingbits systemd[1]: Failed to start MySQL Community Server.
Aug 29 18:22:06 flippingbits systemd[1]: Unit mysql.service entered failed state.
Aug 29 18:22:06 flippingbits systemd[1]: mysql.service failed.
O mais simples seria provavelmente reinstalá-lo.