SSL Certificate problem mirror push

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When setting up a mirror I get the error message:
RemoteError: fatal: unable to access
SSL Certificate problem: unable to get local issuer certificate

I am trying to mirror from gitlab (port 8765) on a server to gitblit (port 8443) on the same server.

I created the repository from the command line by doing git push --set-upstream in the reverse direction.
git push --set-upstream https://git.riskcontrollimited.com:8765/peteryoung/configs.git master

I setup the mirror
https://peteryoung@git.riskcontrollimited.com:8443/r/~peteryoung/configs.git

and supply the correct password

But it always gives the error

13:Close stream to gitaly-ruby
rpc error: Code = unknown desc
Gitlab::Git:RepositoryMirroring::RemoteError: fatal: unable to acces
https://peteryoung@git.riskcontrollimited.com:8443/r/~peteryoung/configs.git/
SSL Certificate problem: unable to get local issuer certificate .

However from the server is looks OK

peter@rcapp05:/$ /opt/gitlab/embedded/bin/openssl s_client -CAfile /etc/gitlab/trusted-certs/rcl_wildcard.crt git.riskcontrollimited.com:8443| more
depth=3 C = GB, ST = Greater Manchester, L = Salford, O = Comodo CA Limited, CN = AAA Certificate Services
verify return:1
depth=2 C = US, ST = New Jersey, L = Jersey City, O = The USERTRUST Network, CN = USERTrust RSA Certification Authority
verify return:1
depth=1 C = GB, ST = Greater Manchester, L = Salford, O = Sectigo Limited, CN = Sectigo RSA Domain Validation Secure Server CA
verify return:1
depth=0 CN = *.riskcontrollimited.com
verify return:1