The main difference between the old and the new OpenVT platform is - apart from a software update, which will in the future hopefully make the platform a safer place - that the URL has changed from virtual.openvt.eu to openvt.eu.
This is important if you have local repositories, which still point at the old URL as origin. In order to update these, open a terminal and browse to the folder of your respective repository. Now, check out the git configuration:
git config --list
This gives you - amongst other git settings - something like
Now change the git configuration:
git remote set-url origin https://openvt.eu/<name_of_your_project>.git
Checking git config again (see above) should now give you the correct remote url. If you are unsure about the correct url, you can also browse to your project on the platform and copy the https cloning link there (blue button) -- the cloning link is exactly the url you need.