Ubuntu20已成功装上pgAdmin4，用浏览器访问报404 Not Found

问题遇到的现象和发生背景

您好！请教个问题，我按照您在《ubuntu20.04安装postgresql12及pgadmin4》中的指引成功安装上pgadmin4，apache也已经启动。但不知为何用浏览器访问 http://localhost/pgadmin4 时提示 404 not found.

问题相关代码，请勿粘贴截图

Creating storage and log directories.
We can now configure the Apache Web server for you. This involves enabling the wsgi module and configuring the pgAdmin 4 application to mount at /pgadmin4. Do you wish to continue (y/n)? y
The Apache web server is not running. We can enable and start the web server for you to finish pgAdmin 4 installation. Continue (y/n)? y
Synchronizing state of apache2.service with SysV service script with /lib/systemd/systemd-sysv-install.
Executing: /lib/systemd/systemd-sysv-install enable apache2
Apache successfully enabled.
Apache successfully started.
You can now start using pgAdmin 4 in web mode at http://127.0.0.1/pgadmin4

运行结果及报错内容

Not Found

The requested URL was not found on this server.

Apache/2.4.41 (Ubuntu) Server at localhost Port 80

我的解答思路和尝试过的方法

我想要达到的结果

问题已解决了，reboot之后就可以。