Hi @MikeMcQ Thanks for your reply.
Yes, I was trying to execute acme.sh with ZeroSSL which failed many times with a Timeout error. Once I tried to setup them manually but it did not work and displayed the message invalid certificate.
Yes, I have acme.sh to obtain certificates from ZeroSSL for other domains but now ZeroSSL is not working so I switched to Let'sEncrypt server.
The last certificate I generated was for basicscomp.com and it is working fine.