Upgrade Foreman 3.6 to 3.7 on Test-System / unable to get local issuer certificate

hi all,

when I try to upgrade foreman from 3.6 to 3.7 I get below error in foreman.log

/Stage[main]/Foreman::Register/Foreman_host[foreman-foreman-server.local]: Could not evaluate: Exception SSL_connect returned=1 errno=0 state=error: certificate verify failed (unable to get local issuer certificate) in get request to: https://foreman-server.local/api/v2/hosts?search=name%3D%22foreman-server.local%22

How can I solve it ?

thank you all