Ubuntu 18.04 更新问题“g_strchug: assertion 'string != NULL' failed”

Question

当我将 Ubuntu 从 16.04 更新到 18.04 时，出现大量错误：

$ sudo apt update && sudo apt upgrade
Hit:1 http://ubuntu.ntc.net.np/ubuntu bionic InRelease        
(appstreamcli:30076): GLib-CRITICAL **: 20:36:32.027: g_strchug: assertion 'string != NULL' failed
(appstreamcli:30076): GLib-CRITICAL **: 20:36:32.027: g_strchomp: assertion 'string != NULL' failed
corrupted double-linked list
Aborted (core dumped)
Reading package lists... Done
E: Problem executing scripts APT::Update::Post-Invoke-Success 'if /usr/bin/test -w /var/cache/app-info -a -e /usr/bin/appstreamcli; then appstreamcli refresh > /dev/null; fi'
E: Sub-process returned an error code

另外，当我检查我的 Ubuntu 版本时，它显示18.04在终端中，但在启动时它显示16.04. 如何解决这个问题？