Upgrade bash without using the terminal to fix iterm issue dyld: Library not loaded: /usr/local/opt/readline/lib/libreadline.6.dylib
This was what helped me, there may be more &quot;correct&quot; ways but if you just need to get it working, give it a go.
Step 1
Open the default Terminal app, then click on Preferences

You will see a path for &quot;Shells open with&quot;

Change the path to
/bin/bash

Close everything out and restart Terminal. Now it should be working, if not, sorry you might have an additional problem that I did not have. But proceed if you are good at this point.
Step 2
proceed to now update bash
brew install bash


Because I ran install I also had to unlink
brew unlink bash


then I ran the command again to install
brew install bash


At this point i started iTerm up again with no problem