TFTP – Path cannot be null

If TFTP gives an error message as

Path cannot be null. Parameter name: path
Illegal characters in path.

It means that you are giving the root directory in the argument. TFTP has a root directory and everything that is being fed to it should be relative to it.

If your root is C:\tftp_root

And your request is C:\tftp_root\my\folder then you should change it to my\folder only.

In case you need to go out of your scope, like C:\Users\foo, then you should do ..\Users\foo