Cannot renew Letsencrypt SSL certificate

Hi guys,

Currently i cant access my website because of the SSL certificate has expired. I’ve tried to renew using certbot, but it give an error.

Cert is due for renewal, auto-renewing...
Renewing an existing certificate
Performing the following challenges:
http-01 challenge for
nginx: [error] invalid PID number "" in "/var/run/"
Waiting for verification...
Challenge failed for domain
http-01 challenge for
Cleaning up challenges
Some challenges have failed.
 - The following errors were reported by the server:
   Type:   unauthorized
   Detail: Invalid response from
   []: "<html>\r\n<head><title>404 Not
   Found</title></head>\r\n<body>\r\n<center><h1>404 Not
   To fix these errors, please make sure that your domain name was
   entered correctly and the DNS A/AAAA record(s) for that domain
   contain(s) the right IP address.

I inherit this system from previous staff that are no longer working with us.
It is highly appreciate if anyone could point me in the right direction.

Do let me know if you need any more information. Thanks

EDIT: There is actually automatic renew previously, but somehow this time around the auto renew failed.

The answer to your post is in the log.
This happens when the domain name is not pointed to the server ip where you’re trying to generate certificate from.