Apple - Why does iterm2 close new sessions immediately?

The default shell was a command shell without command, not a login shell.

Solution:

iTerm->Preferences->Profiles->General->Command

Set radio button to Login shell

For some others go to iTerm > Preferences > Profiles > General > Command.

If the radio button is ‘Login shell’ change the radio button to ‘Command’ and enter

/bin/bash -l

Should look something like this: