现象：Windows，xampp的tomcat启动后，面板start按钮不会变为stop，停止按钮失效。

尝试：通过面板里的“服务和端口”选项，将tomcat的http端口值修改为和tomcat的server.xml里的端口值，即两者要相同。

参考：

• https://stackoverflow.com/questions/45246834/xampp-tomcat-doesnt-start-from-control-panel-starts-only-from-bat
• https://stackoverflow.com/questions/9229026/how-change-the-tomcat-port-in-xampp

问题：centos7系统，用rpm安装的vsftpd，systemctl启动后，ftp localhost 连接会报错：500 OOPS: vsftpd: refusing to run with writable root inside chroot()

尝试：

1. 在vsftpd.conf配置文件里添加 allow_writeable_chroot=YES ，无效
2. 尝试在SELinux里设置权限 setsebool -P allow_ftpd_full_access on ，无效
3. 尝试更换新版本的rpm安装，无效
4. 手动启动vsftpd，在命令行里逐个传递参数测试。当测试到 secure_chroot_dir 指定值时，有效
5. 反查到 /usr/share/empty 目录有全用户写权限（777），取消写权限（755，root属主）。再使用sysmtemctl启动，有效

secure_chroot_dir

This option should be the name of a directory which is empty. Also, the directory should not be writable by the ftp user. This directory is used as a secure chroot() jail at times vsftpd does not require filesystem access.
Default: /usr/share/empty

参考：

• https://security.appspot.com/vsftpd/vsftpd_conf.html
• https://security.appspot.com/vsftpd/FAQ.txt
• https://stackoverflow.com/questions/16102996/error-message-500-oops-vsftpd-refusing-to-run-with-writable-root-inside-chroo

昨晚我家里人说电脑QQ打不开QQ上转发的微信公众号文章，当时夜了，所以我敷衍说，“明天可能自动会好的”。

今天，家里人还是打不开。然后我远程一看，浏览器提示无法打开页面。查看浏览器里显示的网址，是url.cn的，是腾讯公司常用来跳转网址的短域名。尝试ping url.cn的域名，返回127.0.0.1的应答。再查看本机的hosts文件内容，正常。查看当前的dns服务器地址是120.196.165.24和211.136.192.6，是从路由器自动获取到的。又查路由器的配置信息，dns是从宽带拨号里自动获取到的。120.196.165.24对应的rDNS值是ns6.gd.cnmobile.net，看来移动宽带自动分配的dns服务器工作不正常。所以，最后是将电脑的IPv4配置信息中的dns服务器手动更改为阿里云的公共dns服务器223.5.5.5后就可以打开url.cn的跳转网址了。

C:\>nslookup url.cn 120.196.165.24
服务器:  ns6.gd.cnmobile.net
Address:  120.196.165.24

DNS request timed out.
    timeout was 2 seconds.
名称:    url.cn
Address:  ::1

问题：非管理员的普通用户在“控制面板”添加日文微软输入法后，只能输入英文字母abc，不能输入日文平假字あいさつと。

尝试：以管理员账户登录后，在“控制面板”添加日文微软输入法后，会提示下载语言包，完成下载后（显示“已安装语言包”），非管理员账户也能输入日文平假字なに了。

参考：https://www.bilibili.com/read/cv3562323/

环境：腾讯云香港机，iredmail 1.3.1，centos7

问题：iredmail安装完成后，在浏览器里访问 iredadmin 提示 Internal Server Error 出错。

过程：查看 /var/log/message 内容，

Jul 22 13:35:30 mail uwsgi: *** Operational MODE: preforking ***
Jul 22 13:35:30 mail uwsgi: Traceback (most recent call last):
Jul 22 13:35:30 mail uwsgi:  File "iredadmin.py", line 9, in <module>
Jul 22 13:35:30 mail uwsgi:
Jul 22 13:35:30 mail uwsgi: from libs import iredbase
Jul 22 13:35:30 mail uwsgi:  File "/opt/www/iRedAdmin-1.0/libs/iredbase.py", line 7, in <module>
Jul 22 13:35:30 mail uwsgi:
Jul 22 13:35:30 mail uwsgi: import web
Jul 22 13:35:30 mail uwsgi: ImportError
Jul 22 13:35:30 mail uwsgi: :
Jul 22 13:35:30 mail uwsgi: No module named web
Jul 22 13:35:30 mail uwsgi:
Jul 22 13:35:30 mail uwsgi: unable to load app 0 (mountpoint='') (callable not found or import error)
Jul 22 13:35:30 mail uwsgi: *** no app loaded. going in full dynamic mode ***

回查安装过程中，有相关的错误提示内容：

Complete!
[ INFO ] Installing required Python-3 modules with pip3: web.py>=0.51 web.py>=0.51
WARNING: Running pip install with root privileges is generally not a good idea. Try `pip3 install --user` instead.
Collecting web.py>=0.51
  The repository located at mirrors.tencentyun.com is not a trusted or secure host and is being ignored. If this repository is available via HTTPS it is recommended to use HTTPS instead, otherwise you may silence this warning and allow it anyways with '--trusted-host mirrors.tencentyun.com'.
  Could not find a version that satisfies the requirement web.py>=0.51 (from versions: )
No matching distribution found for web.py>=0.51
[ INFO ] Installing required Python-2 modules with pip2: web.py>=0.51 more-itertools==5.0.0 web.py>=0.51 more-itertools==5.0.0
Collecting web.py>=0.51
  The repository located at mirrors.tencentyun.com is not a trusted or secure host and is being ignored. If this repository is available via HTTPS it is recommended to use HTTPS instead, otherwise you may silence this warning and allow it anyways with '--trusted-host mirrors.tencentyun.com'.
  Could not find a version that satisfies the requirement web.py>=0.51 (from versions: )
No matching distribution found for web.py>=0.51
You are using pip version 8.1.2, however version 20.1.1 is available.
You should consider upgrading via the 'pip install --upgrade pip' command.

那么可尝试手工安装python的相关包，
pip3 install web.py>=0.51
pip2 install web.py>=0.51 more-itertools==5.0.0

然后再重启相应服务（iredamin和iredpad等），或重启系统后测试，可以正常登录到iredadmin进行管理了。

参考：https://forum.iredmail.org/topic17082-internal-server-error-iredadmin.html