Cannot connect to localhost when running Django

Question

I am trying to run my Django project and I encountered the following problem:

^C(venv) tests-MacBook-Pro-2:hearinsights morganlai$ python manage.py runserver
Performing system checks...

System check identified no issues (0 silenced).
Unhandled exception in thread started by <function wrapper at 0x103fc46e0>
Traceback (most recent call last):
  File "/Users/morganlai/Desktop/hearinsights-heap/venv/lib/python2.7/site-packages/django/utils/autoreload.py", line 226, in wrapper
    fn(*args, **kwargs)
  File "/Users/morganlai/Desktop/hearinsights-heap/venv/lib/python2.7/site-packages/django/core/management/commands/runserver.py", line 117, in inner_run
    self.check_migrations()
  File "/Users/morganlai/Desktop/hearinsights-heap/venv/lib/python2.7/site-packages/django/core/management/commands/runserver.py", line 163, in check_migrations
    executor = MigrationExecutor(connections[DEFAULT_DB_ALIAS])
  File "/Users/morganlai/Desktop/hearinsights-heap/venv/lib/python2.7/site-packages/django/db/migrations/executor.py", line 20, in __init__
    self.loader = MigrationLoader(self.connection)
  File "/Users/morganlai/Desktop/hearinsights-heap/venv/lib/python2.7/site-packages/django/db/migrations/loader.py", line 49, in __init__
    self.build_graph()
  File "/Users/morganlai/Desktop/hearinsights-heap/venv/lib/python2.7/site-packages/django/db/migrations/loader.py", line 176, in build_graph
    self.applied_migrations = recorder.applied_migrations()
  File "/Users/morganlai/Desktop/hearinsights-heap/venv/lib/python2.7/site-packages/django/db/migrations/recorder.py", line 65, in applied_migrations
    self.ensure_schema()
  File "/Users/morganlai/Desktop/hearinsights-heap/venv/lib/python2.7/site-packages/django/db/migrations/recorder.py", line 52, in ensure_schema
    if self.Migration._meta.db_table in self.connection.introspection.table_names(self.connection.cursor()):
  File "/Users/morganlai/Desktop/hearinsights-heap/venv/lib/python2.7/site-packages/django/db/backends/base/base.py", line 231, in cursor
    cursor = self.make_debug_cursor(self._cursor())
  File "/Users/morganlai/Desktop/hearinsights-heap/venv/lib/python2.7/site-packages/django/db/backends/base/base.py", line 204, in _cursor
    self.ensure_connection()
  File "/Users/morganlai/Desktop/hearinsights-heap/venv/lib/python2.7/site-packages/django/db/backends/base/base.py", line 199, in ensure_connection
    self.connect()
  File "/Users/morganlai/Desktop/hearinsights-heap/venv/lib/python2.7/site-packages/django/db/utils.py", line 95, in __exit__
    six.reraise(dj_exc_type, dj_exc_value, traceback)
  File "/Users/morganlai/Desktop/hearinsights-heap/venv/lib/python2.7/site-packages/django/db/backends/base/base.py", line 199, in ensure_connection
    self.connect()
  File "/Users/morganlai/Desktop/hearinsights-heap/venv/lib/python2.7/site-packages/django/db/backends/base/base.py", line 171, in connect
    self.connection = self.get_new_connection(conn_params)
  File "/Users/morganlai/Desktop/hearinsights-heap/venv/lib/python2.7/site-packages/django/db/backends/postgresql/base.py", line 175, in get_new_connection
    connection = Database.connect(**conn_params)
  File "/Users/morganlai/Desktop/hearinsights-heap/venv/lib/python2.7/site-packages/psycopg2/__init__.py", line 164, in connect
    conn = _connect(dsn, connection_factory=connection_factory, async=async)
django.db.utils.OperationalError: could not connect to server: Connection refused
    Is the server running on host "127.0.0.1" and accepting
    TCP/IP connections on port 5432?

I have tried to start and restart the postgres database following the instructions here: How to start PostgreSQL server on Mac OS X?

After restart the server, the problem still occured:

tests-MacBook-Pro-2:hearinsights morganlai$ pg_ctl -D /usr/local/var/postgres stop -s -m fast
pg_ctl: PID file "/usr/local/var/postgres/postmaster.pid" does not exist
Is server running?
tests-MacBook-Pro-2:hearinsights morganlai$ pg_ctl -D /usr/local/var/postgres -l /usr/local/var/postgres/server.log start
server starting

I would encounter this problem every single time when I restarted my mac and the solution provided by that article usually worked in the past. Since it is not working this time, I wonder it might be some other problems.

Answer 1

Try to uninstall the current postgres files. And install it from scratch using homebrew:

https://launchschool.com/blog/how-to-install-postgresql-on-a-mac

This might fix your issue.