Fetching Ubuntu's OpenPGP keys for verification fails with "not a key ID: skipping"
This seems to be same issue others had with GnuPG on Windows and Mac OS X, reported on Super User in the question "gpg2 not a key id: skipping” when trying to download public keys":
While the command works fine under GnuPG on Linux, it fails in Windows. I've been able to make it work by removing all spaces:
gpg --keyserver hkp://keyserver.ubuntu.com --recv-keys 843938DF228D22F7B3742BC0D94AA3F0EFE21092C5986B4F1257FFA86632CBA746181433FBB75451
(the quotes are not required any more, either; so I removed them).
If you really want to verify against signatures from Ubuntu, you obviously shouldn't copy/paste this specific command line as is, but remove the space from the original Ubuntu page on your own.
The solution will be the same, and you should get the command running by removing the spaces in the fingerprints (the hexadecimal numbers).