use -i option and pdb:
python -i manage.py command_name
failed or not , you will have a python repl, so you can use pdb to jump into the stacks raising exception:
return executor(sql, params, many, context)
File "/home/gary/PycharmProjects/borges-env/lib/python3.6/site-packages/django/db/backends/utils.py", line 84, in _execute
return self.cursor.execute(sql, params)
File "/home/gary/PycharmProjects/borges-env/lib/python3.6/site-packages/django/db/utils.py", line 89, in __exit__
raise dj_exc_value.with_traceback(traceback) from exc_value
File "/home/gary/PycharmProjects/borges-env/lib/python3.6/site-packages/django/db/backends/utils.py", line 84, in _execute
return self.cursor.execute(sql, params)
django.db.utils.DataError: value too long for type character varying(10)
>>> import pdb
>>> pdb.pm()
> /home/gary/PycharmProjects/borges-env/lib/python3.6/site-packages/django/db/backends/utils.py(84)_execute()
-> return self.cursor.execute(sql, params)
(Pdb) param
blablabalablabalablbalbalabla
import traceback; traceback.print_exc()or just remove wrong code from try/except block temporary.import pdb; pdb.set_trace()as the first line in management command and step through the code.