Recently found a strange problem with website use   The free certificate of let’s encrypt is normal when the browser accesses, but an error is reported when WGet. The error information is as follows:

wget https://www.example.com

--2021-11-16 13:00:42--  https://www.example.com/
Resolving www.example.com (www.example.com)... 47.91.21.201
Connecting to www.example.com (www.example.com)|47.21.17.201|:443... connected.
ERROR: cannot verify www.example.com's certificate, issued by ‘/C=US/O=Let's Encrypt/CN=R3’:
  Issued certificate has expired.
To connect to www.example.com insecurely, use `--no-check-certificate'.

After a wave of online search, I didn’t find any effective solutions. The two methods are effective.

1. Install software

yum install -y ca-certificates

2. Replacement of issuing authority

Because I use the certificate issued by acme.sh, I use zerossl server by default when issuing the certificate, and I specify it specifically   Let’s encrypt directory server, so just remove the specified server here. Use zereossl as the issuing authority.