The unauthenticated git protocol on port 9418 is no longer supported

Course Questions Drone Programming
1

I used this cmd…
git submodule update --init --recursive
for updating the submodules present in the ardupilot…
I am getting a fatal error of
"
The unauthenticated git protocol on port 9418 is no longer supported"

I tried many different things can you suggest something that will slove it

2

It would be helpful to list what ‘many different things’ are so people won’t spend time doing the same.
There seems to be a number of solutions in a simple web search?