Rails: may have been in progress in another thread when fork() was called

It is not enough running the workaround command before rails console.

The following solution worked for me (follow this instructions):

If you encounter this error, you can add the code below to your .bash_profile located in your home directory to fix the issue.

export OBJC_DISABLE_INITIALIZE_FORK_SAFETY=YES

1. Open your terminal
2. Navigate to your home directory by typing cd ~
3. Open .bash_profile in an editor (code for VS Code, atom for Atom, vim, nano, etc.)
   nano .bash_profile
4. Copy and paste in export OBJC_DISABLE_INITIALIZE_FORK_SAFETY=YES in your file (be sure it is above the RVM section at the bottom of the file!)

* THIS IS IMPORTANT *
In my case into .bash_profile it is something like this:

export OBJC_DISABLE_INITIALIZE_FORK_SAFETY=YES

[[ -s "$HOME/.rvm/scripts/rvm" ]] && source "$HOME/.rvm/scripts/rvm" # Load RVM$

Save the file and quit all editor and terminal sessions.
Reopen your editor and everything should now work normally.

I found this solution at this link Kody Clemens Personal Blog