Searched and found the following post by matidau. I tried the recommendation and the issue is RESOLVED!
Steps I took from matidau’s post:
sudo apt list python*blinker*
sudo apt remove python3-blinker
sudo /usr/local/lib/mailinabox/env/bin/pip install --upgrade rtyaml "email_validator>=1.0.0" "exclusiveprocess" flask dnspython python-dateutil expiringdict gunicorn qrcode[pil] pyotp "idna>=2.0.0" "cryptography==37.0.2" psutil postfix-mta-sts-resolver b2sdk boto3
re-run Mail-in-a-Box setup.
Full post can be found here:
Thank you matidau!
Best regards