scm-sync-configuration had two bad urls. I was able to figure out one of them, but not the other.
On https://10.0.0.61:8443/jenkins/configure, the link “Reload” pointed to https://10.0.0.61:8443/plugin/scm-sync-configuration/reloadAllFilesFromScm . It was missing the jenkins layer. https://10.0.0.61:8443/jenkins/plugin/scm-sync-configuration/reloadAllFilesFromScm worked.
On https://10.0.0.61:8443/jenkins/plugin/scm-sync-configuration/reloadAllFilesFromScm , the link “here” pointed to https://10.0.0.61:8443/reload . I wasn't able to figure that one out. I wound up restoring the job by hand.