Troubleshooting

Azure REST API error at GetSite or Dns01Precondition error

The role assignment to the target resource group may be incorrect or not yet active. It may take up to 30 minutes for the IAM settings to take effect.

CheckDnsChallenge failed: _acme-challenge.{domain}.com value is not correct

In order for the certificate to be created, the Acmebot needs to create a TXT DNS record for _acme-challenge in Azure DNS. This error occurs when the TXT record isn't being served. One cause of this may be that the nameservers for your domain may be pointing to the domain registrar, rather than Azure DNS. Make sure that you have properly delegated the domain to Azure DNS: Host your domain in Azure DNS

CheckHttpChallenge failed: http://{domain}/.well-known/acme-challenge/{challenge} is InternalServerError status code

This seems like an URL rewrite error. Try setting inheritInChildApplications="false" in the web.config under wwwroot.

https://www.hanselman.com/blog/ChangingASPNETWebconfigInheritanceWhenMixingVersionsOfChildApplications.aspx