Error on Creating New Customer on Fresh Installation of ERPNext

On a fresh installation of ERPNext on Debian 9.13, on CRM Module trying to create a New Customer, always I receive the Server error [NameError: name ‘basestring’ is not defined] as in the picture.

It may help to say what version ERPNext and how it was installed.

I beg your pardon, I forgot to mention that the error is given on v12 on Frappe-ERPNext that was installed with Easy Install following the command
sudo python3 --production --site [site name].[domain] --version 12 --user erpnext --bench-name erpnext-prd --verbose 2>&1 | tee --append erpnext-install.log

provided by
curl “” -o

On a new repeated fresh installation on Debian 13 with Easy Install on version 12 of ERPNext v12.10.1 and Frappe v12.8.4 the error is not ocurring anymore.