django-main-thread error when running manage.py runserver

Question

I've made some changes to my code while trying to deploy my django app on digital ocean, and now when I try to test my code in my local server, I get this error:

(my_chaburah) ~/Desktop/Code/my_chaburah (main)
$ python3 manage.py runserver
Watching for file changes with StatReloader
Exception in thread django-main-thread:
Traceback (most recent call last):
  File "/Users/almoni/.local/share/virtualenvs/my_chaburah-AiCSV-sC/lib/python3.9/site-packages/django/db/backends/postgresql/base.py", line 24, in <module>
    import psycopg2 as Database
  File "/Users/almoni/.local/share/virtualenvs/my_chaburah-AiCSV-sC/lib/python3.9/site-packages/psycopg2/__init__.py", line 51, in <module>
    from psycopg2._psycopg import (                     # noqa
ImportError: dlopen(/Users/almoni/.local/share/virtualenvs/my_chaburah-AiCSV-sC/lib/python3.9/site-packages/psycopg2/_psycopg.cpython-39-darwin.so, 0x0002): Library not loaded: '/opt/homebrew/opt/postgresql/lib/libpq.5.dylib'
  Referenced from: '/Users/almoni/.local/share/virtualenvs/my_chaburah-AiCSV-sC/lib/python3.9/site-packages/psycopg2/_psycopg.cpython-39-darwin.so'
  Reason: tried: '/opt/homebrew/opt/postgresql/lib/libpq.5.dylib' (no such file), '/usr/local/lib/libpq.5.dylib' (no such file), '/usr/lib/libpq.5.dylib' (no such file), '/opt/homebrew/Cellar/postgresql@14/14.5_5/lib/libpq.5.dylib' (no such file), '/usr/local/lib/libpq.5.dylib' (no such file), '/usr/lib/libpq.5.dylib' (no such file)

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/opt/homebrew/Cellar/python@3.9/3.9.15/Frameworks/Python.framework/Versions/3.9/lib/python3.9/threading.py", line 980, in _bootstrap_inner
    self.run()
  File "/opt/homebrew/Cellar/python@3.9/3.9.15/Frameworks/Python.framework/Versions/3.9/lib/python3.9/threading.py", line 917, in run
    self._target(*self._args, **self._kwargs)
  File "/Users/almoni/.local/share/virtualenvs/my_chaburah-AiCSV-sC/lib/python3.9/site-packages/django/utils/autoreload.py", line 64, in wrapper
    fn(*args, **kwargs)
  File "/Users/almoni/.local/share/virtualenvs/my_chaburah-AiCSV-sC/lib/python3.9/site-packages/django/core/management/commands/runserver.py", line 125, in inner_run
    autoreload.raise_last_exception()
  File "/Users/almoni/.local/share/virtualenvs/my_chaburah-AiCSV-sC/lib/python3.9/site-packages/django/utils/autoreload.py", line 87, in raise_last_exception
    raise _exception[1]
  File "/Users/almoni/.local/share/virtualenvs/my_chaburah-AiCSV-sC/lib/python3.9/site-packages/django/core/management/__init__.py", line 398, in execute
    autoreload.check_errors(django.setup)()
  File "/Users/almoni/.local/share/virtualenvs/my_chaburah-AiCSV-sC/lib/python3.9/site-packages/django/utils/autoreload.py", line 64, in wrapper
    fn(*args, **kwargs)
  File "/Users/almoni/.local/share/virtualenvs/my_chaburah-AiCSV-sC/lib/python3.9/site-packages/django/__init__.py", line 24, in setup
    apps.populate(settings.INSTALLED_APPS)
  File "/Users/almoni/.local/share/virtualenvs/my_chaburah-AiCSV-sC/lib/python3.9/site-packages/django/apps/registry.py", line 116, in populate
    app_config.import_models()
  File "/Users/almoni/.local/share/virtualenvs/my_chaburah-AiCSV-sC/lib/python3.9/site-packages/django/apps/config.py", line 304, in import_models
    self.models_module = import_module(models_module_name)
  File "/opt/homebrew/Cellar/python@3.9/3.9.15/Frameworks/Python.framework/Versions/3.9/lib/python3.9/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1030, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1007, in _find_and_load
  File "<frozen importlib._bootstrap>", line 986, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 680, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 850, in exec_module
  File "<frozen importlib._bootstrap>", line 228, in _call_with_frames_removed
  File "/Users/almoni/.local/share/virtualenvs/my_chaburah-AiCSV-sC/lib/python3.9/site-packages/django/contrib/auth/models.py", line 3, in <module>
    from django.contrib.auth.base_user import AbstractBaseUser, BaseUserManager
  File "/Users/almoni/.local/share/virtualenvs/my_chaburah-AiCSV-sC/lib/python3.9/site-packages/django/contrib/auth/base_user.py", line 49, in <module>
    class AbstractBaseUser(models.Model):
  File "/Users/almoni/.local/share/virtualenvs/my_chaburah-AiCSV-sC/lib/python3.9/site-packages/django/db/models/base.py", line 141, in __new__
    new_class.add_to_class("_meta", Options(meta, app_label))
  File "/Users/almoni/.local/share/virtualenvs/my_chaburah-AiCSV-sC/lib/python3.9/site-packages/django/db/models/base.py", line 369, in add_to_class
    value.contribute_to_class(cls, name)
  File "/Users/almoni/.local/share/virtualenvs/my_chaburah-AiCSV-sC/lib/python3.9/site-packages/django/db/models/options.py", line 235, in contribute_to_class
    self.db_table, connection.ops.max_name_length()
  File "/Users/almoni/.local/share/virtualenvs/my_chaburah-AiCSV-sC/lib/python3.9/site-packages/django/utils/connection.py", line 15, in __getattr__
    return getattr(self._connections[self._alias], item)
  File "/Users/almoni/.local/share/virtualenvs/my_chaburah-AiCSV-sC/lib/python3.9/site-packages/django/utils/connection.py", line 62, in __getitem__
    conn = self.create_connection(alias)
  File "/Users/almoni/.local/share/virtualenvs/my_chaburah-AiCSV-sC/lib/python3.9/site-packages/django/db/utils.py", line 208, in create_connection
    backend = load_backend(db["ENGINE"])
  File "/Users/almoni/.local/share/virtualenvs/my_chaburah-AiCSV-sC/lib/python3.9/site-packages/django/db/utils.py", line 113, in load_backend
    return import_module("%s.base" % backend_name)
  File "/opt/homebrew/Cellar/python@3.9/3.9.15/Frameworks/Python.framework/Versions/3.9/lib/python3.9/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "/Users/almoni/.local/share/virtualenvs/my_chaburah-AiCSV-sC/lib/python3.9/site-packages/django/db/backends/postgresql/base.py", line 28, in <module>
    raise ImproperlyConfigured("Error loading psycopg2 module: %s" % e)
django.core.exceptions.ImproperlyConfigured: Error loading psycopg2 module: dlopen(/Users/almoni/.local/share/virtualenvs/my_chaburah-AiCSV-sC/lib/python3.9/site-packages/psycopg2/_psycopg.cpython-39-darwin.so, 0x0002): Library not loaded: '/opt/homebrew/opt/postgresql/lib/libpq.5.dylib'
  Referenced from: '/Users/almoni/.local/share/virtualenvs/my_chaburah-AiCSV-sC/lib/python3.9/site-packages/psycopg2/_psycopg.cpython-39-darwin.so'
  Reason: tried: '/opt/homebrew/opt/postgresql/lib/libpq.5.dylib' (no such file), '/usr/local/lib/libpq.5.dylib' (no such file), '/usr/lib/libpq.5.dylib' (no such file), '/opt/homebrew/Cellar/postgresql@14/14.5_5/lib/libpq.5.dylib' (no such file), '/usr/local/lib/libpq.5.dylib' (no such file), '/usr/lib/libpq.5.dylib' (no such file)

I have no idea what I'm looking at -- I've never seen this kind of error before. No idea where to even start. Because of my confusion I'm not sure what parts of my code I should post to help elaborate. Just want to get my app working again before I try to deploy.

I'm just guessing but I assume it has something to do with virtual environments or pip installations, although I'm concerened it's because I manually deleted files that I perhaps shouldn't have.

Answer 1

It tried to load libpq.5.dylib from the symlink /opt/homebrew/opt/postgresql/lib/libpq.5.dylib but could not find the file, so you need to update it:

# TODO: get this from the error, after "Library not loaded:"
SYMLINK_PATH="/opt/homebrew/opt/postgresql/lib/libpq.5.dylib"

# TODO: find this in your machine. The version maybe different than mine
DESTINATION_PATH="/opt/homebrew/opt/postgresql/lib/postgresql@14/libpq.5.dylib"

sudo mv $SYMLINK_PATH $SYMLINK_PATH.old
sudo ln -s $DESTINATION_PATH $SYMLINK_PATH