When trying a remote operation in TortoiseGit 2.3.0.0 on windows 10, I get:
fatal: unable to access 'https://github.com/username/repo.git/': SSL certificate problem: unable to get local issuer certificate
There seems to be no problem doing things from the git command line, so it seems to be a TortoiseGit problem.
I recently upgraded git from an old version (1.5 ish) to 2.10.0. - this may be when the problems started. I notice that there have been some changes relating to certificates.
I have tried using http.sslVerify false as a diagnostic tactic, but that doesn't make the problem go away which worked once I put the setting in my local (not global) config, though I got some 'cannot spawn sh' errors.
I've tried uninstalling and reinstalling TortoiseGit.