python - Flask-Login `user_callback` not being set, `user_loader` seems to be called twice -

i'm building simple python application using flask. i'm running trouble flask-login. seemed working until upgraded projects dependencies morning , can't figure out going on.

the error i'm getting typeerror: 'nonetype' object not callable. here full stack trace:

traceback (most recent call last): file "c:\users\acrowder\venv\lib\site-packages\flask\app.py", line 1836, in __call__ return self.wsgi_app(environ, start_response) file "c:\users\acrowder\venv\lib\site-packages\flask\app.py", line 1820, in wsgi_app response = self.make_response(self.handle_exception(e)) file "c:\users\acrowder\venv\lib\site-packages\flask\app.py", line 1403, in handle_exception reraise(exc_type, exc_value, tb) file "c:\users\acrowder\venv\lib\site-packages\flask\_compat.py", line 33, in reraise raise value file "c:\users\acrowder\venv\lib\site-packages\flask\app.py", line 1817, in wsgi_app response = self.full_dispatch_request() file "c:\users\acrowder\venv\lib\site-packages\flask\app.py", line 1477, in full_dispatch_request rv = self.handle_user_exception(e) file "c:\users\acrowder\venv\lib\site-packages\flask\app.py", line 1381, in handle_user_exception reraise(exc_type, exc_value, tb) file "c:\users\acrowder\venv\lib\site-packages\flask\_compat.py", line 33, in reraise raise value file "c:\users\acrowder\venv\lib\site-packages\flask\app.py", line 1475, in full_dispatch_request rv = self.dispatch_request() file "c:\users\acrowder\venv\lib\site-packages\flask\app.py", line 1461, in dispatch_request return self.view_functions[rule.endpoint](**req.view_args) file "c:\code\crowdcontrol\app\site\views.py", line 52, in page return render_template(template_path, page=the_page, menu=menu) file "c:\users\acrowder\venv\lib\site-packages\flask\templating.py", line 126, in render_template ctx.app.update_template_context(context) file "c:\users\acrowder\venv\lib\site-packages\flask\app.py", line 716, in update_template_context context.update(func()) file "c:\users\acrowder\venv\lib\site-packages\flask_login.py", line 825, in _user_context_processor return dict(current_user=_get_user()) file "c:\users\acrowder\venv\lib\site-packages\flask_login.py", line 794, in _get_user current_app.login_manager._load_user() file "c:\users\acrowder\venv\lib\site-packages\flask_login.py", line 363, in _load_user return self.reload_user() file "c:\users\acrowder\venv\lib\site-packages\flask_login.py", line 325, in reload_user user = self.user_callback(user_id) typeerror: 'nonetype' object not callable 

here's init.py app:

import os flask import flask flask.ext.bootstrap import bootstrap flask.ext.mail import mail flask.ext.moment import moment flask.ext.sqlalchemy import sqlalchemy flask.ext.login import loginmanager config import config app.jinja_filters import format_datetime  bootstrap = bootstrap() mail = mail() moment = moment() db = sqlalchemy()  login_manager = loginmanager()  def create_app(config_name):     the_app = flask(__name__)     the_app.config.from_object(config[config_name])     config[config_name].init_app(the_app)      bootstrap.init_app(the_app)     mail.init_app(the_app)     moment.init_app(the_app)     db.init_app(the_app)      # let's set our login handlers     import app.login_handlers     login_manager.session_protection = 'strong'     login_manager.login_view = 'auth.login'     login_manager.init_app(the_app)      the_app.jinja_env.filters['datetime'] = format_datetime      app.site import site site_blueprint     the_app.register_blueprint(site_blueprint)      app.blog import blog blog_blueprint     the_app.register_blueprint(blog_blueprint)      app.admin import admin admin_blueprint     the_app.register_blueprint(admin_blueprint, url_prefix="/admin")      app.auth import auth auth_blueprint     the_app.register_blueprint(auth_blueprint, url_prefix="/auth")      return the_app   app = create_app(os.getenv('flask_config') or 'default')  if __name__ == "__main__":     app.run() 

and here's login_handlers.py file:

from app import login_manager app.models import user   @login_manager.user_loader def load_user(user_id):     return user.query.get(int(user_id)) 

i've put in breakpoint in flask_login.py on line 216, , seems called twice. can't figure out where.