I just submitted my UK tourist visa application. However I forgot to sign the printed online form although I made an e-signature after my fingerprints registration. Does this lead to a refusal?
No, your application will not be refused due to the lack of a signature.
It will not be refused. If they decide it's a show-stopper they will reject it; i.e., send it back to the VFS so you can sign it. It will have a short fuse on it because they do not want your evidence to get stale. A rejection is not the same as a refusal, so it's not a big problem.
Source: comment on this TSE thread by user Gayot Fow