Dockerfile from ubuntu:22.04 apt unable to locate package python3 [duplicate]

When I docker build this:

FROM ubuntu:22.04RUN apt-get install -y python3

I get

Step 1/2 : FROM ubuntu:22.04 ---> c6b84b685f35Step 2/2 : RUN apt-get install -y python3 ---> Running in d1f4eff8d024Reading package lists...Building dependency tree...Reading state information...E: Unable to locate package python3

What's wrong?