manjaro更新升级提示error: failed to update core (unable to lock database)的解决方法

在使用manjaro的pacman命令做系统或软件升级时，遇到了如下的报错，从而导致不能正常更新升级:

error: failed to update core (unable to lock database)
error: failed to update extra (unable to lock database)
error: failed to update community (unable to lock database)
error: failed to update multilib (unable to lock database)
error: failed to update archlinuxcn (unable to lock database)
error: failed to update antergos (unable to lock database)
error: failed to synchronize all databases

查阅相关资料后,找到原因:
这是Pacman数据库因之前的操作异常而被锁定，需要我们进行手动解锁
可执行如下命令:
rm -f /var/lib/pacman/db.lck
然后重新执行sudo pacman -Syu即可

 core is up to date
 extra is up to date                0.0   B  0.00B/s 00:00 [--------------------------------]   0%
 community is up to date            0.0   B  0.00B/s 00:00 [--------------------------------]   0%
 multilib is up to date
 archlinuxcn is up to date          0.0   B  0.00B/s 00:00 [--------------------------------]   0%
 antergos is up to date
:: Starting full system upgrade...
resolving dependencies...
looking for conflicting packages...

Packages (3) firefox-67.0.3-0  firefox-i18n-zh-cn-67.0.3-0  google-chrome-75.0.3770.100-1

Total Download Size:   105.17 MiB
Total Installed Size:  379.93 MiB
Net Upgrade Size:       12.15 MiB

:: Proceed with installation? [Y/n] y
:: Retrieving packages...
 firefox-67.0.3-0-x86_64           46.9 MiB  26.5M/s 00:02 [################################] 100%
 firefox-i18n-zh-cn-67.0.3-0-any  466.4 KiB  65.1M/s 00:00 [################################] 100%
 google-chrome-75.0.3770.100...    57.8 MiB  4.21M/s 00:14 [################################] 100%
(3/3) checking keys in keyring                             [################################] 100%
(3/3) checking package integrity                           [################################] 100%
(3/3) loading package files                                [################################] 100%
(3/3) checking for file conflicts                          [################################] 100%
(3/3) checking available disk space                        [################################] 100%
:: Running pre-transaction hooks...
(1/1) Remove Firefox Distribution Settings
:: Processing package changes...
(1/3) upgrading firefox                                    [################################] 100%
(2/3) upgrading firefox-i18n-zh-cn                         [################################] 100%
(3/3) upgrading google-chrome                              [################################] 100%