更新snap-store出现如下报错：
Unable to Update "Snap Store":
(null): cannot refresh "snap-store": snap "snap-store" has been running apps (ubuntu-software)
解决方法在终端（terminal)中输入
killall snap-store sudo snap refresh snap-store
即可更新完毕！
参考链接：
解决方法是
killall snap-store
sudo snap refresh snap-store即可更新完毕