Invalid SSL certificate when pushing to Git server

I am running Gitblit on a Windows Server and am trying to push data to a repository from another machine on the network. I have used a SSL certificate (not self signed, but I think signed by my company? Not really sure how that works but Chrome, IE, etc. see it is identity verified).

The server that runs Gitblit is named itscm and on the developer's desktop I am using this URL to push data via TortoiseGit:

git.exe push --progress  "https://itscm:8234/git/TestRepo.git" master

However, I get this error:

fatal: unable to access 'https://itscm:8234/git/TestRepo.git/': SSL certificate problem: self signed certificate in certificate chain

When I go to that address in chrome, I get a 404 on the page, BUT I can see that the padlock in the URL bar is green. When I click the padlock I see that the identity is verified. I don't understand how my browser sees this certificate as valid but when I try to push data to it via Git, it fails.

Solution

Git for Windows has its own trust store of trusted certificates which is normally located in the file

Git for Windows <=1.9: [Git installdir]\bin\curl-ca-bundle.crt (e.g., C:\Program Files (x86)\Git\bin\curl-ca-bundle.crt; configured by the key http.sslCAinfo in [Git installdir]\etc\gitconfig).
Git for Windows >= 2.0: [Git installdir]\mingwXX\ssl\certs\ca-bundle.crt where XX stands for 32 or 64 (e.g., C:\Program Files\Git\mingw64\ssl\certs\ca-bundle.crt; configured by the key http.sslCAinfo in git config, e.g. C:\Program Files\Git\etc or your global/local config).

Disabling checking of certificates (e.g., by setting git config http.sslVerify false) is not a good idea and might be extremely dangerous (as all security checks are disabled and MitM attacks are easily possible - depending where this is set it applies for all new https connections).

In order to add a certificate (may it be a self-signed one or another root certificate) to this trust store in order to automatically trust it, you have to perform the following steps (the first five steps are just to gather the certificate, this can also be done with your favorite browser, but might require different tasks):

Open the URL of the site in Microsoft Edge
Click on the lock symbol in the local bar and choose "Connection is safe" and then click on the certificate symbol.
(Optional) Select the certificate you want to trust on the certificate chain (third tab) and open it
Go to the second tab "Details"
Click on "Save to file", choose "Base64-encoded X.509 (.CER)" and save it with a unique name (remember that name; a name w/o spaces is recommended).
Now you have several options
1. Use a separate certificate trust store which only contains your just downloaded cert, by executing git config --global http.sslCAinfo "[yourfilename]" in a cli shell in order to only use this certificate as the trust store.
2. Use a separate certificate trust store which contains your just downloaded cert and all certificates from the git trust store, by appending all content from the system trust store file (path see above) and then execute git config --global http.sslCAinfo "[yourfilename]" in a cli shell in order to use this new trust store.
3. Update the system certificate file, by appending the content of your just saved file to [path-to-git-trust-store-crt-file] (e.g. by type [yourfilename] >> [path-to-git-trust-store-crt-file] in a cli shell running with administrative rights) OR using notepad (make a copy of the ca-bundle.crt file on desktop, append the content of the downlaoded .crt file and then copy it back). Disadvantage: changes might get overwritten on git update

Done. Now, this certificate is in the trust store of Git for Windows.

Recent versions of Git for Windows can use also Windows certificate store which might be more convenient in a corporate environment. This can be configured on installation.