openssl TXT_DB error number 2

报错

Sign the certificate? [y/n]:y
failed to update database
TXT_DB error number 2
unable to write 'random state'

查阅网络解决方案，原因如下：

This thing happens when certificates share common data. You cannot have two 
certificates that look otherwise the same.

demoCA下 index.txt 已存在相同重复的记录，生成csr时注意区别一下新的证书即可