RE: FATAL ERROR: The application server could not be contacted.

Traceback (most recent call last):

  File "C:/Program Files/PostgreSQL/10/pgAdmin 4/web/pgAdmin4.py", line 70, in <module>

    app = create_app()

  File "C:\Program Files\PostgreSQL\10\pgAdmin 4\web\pgadmin\__init__.py", line 317, in create_app

    db_upgrade(app)

  File "C:\Program Files\PostgreSQL\10\pgAdmin 4\web\pgadmin\setup\db_upgrade.py", line 25, in db_upgrade

    flask_migrate.upgrade(migration_folder)

  File "C:/Program Files/PostgreSQL/10/pgAdmin 4/venv/Lib/site-packages\flask_migrate\__init__.py", line 259, in upgrade

    command.upgrade(config, revision, sql=sql, tag=tag)

  File "C:/Program Files/PostgreSQL/10/pgAdmin 4/venv/Lib/site-packages\alembic\command.py", line 254, in upgrade

    script.run_env()

  File "C:/Program Files/PostgreSQL/10/pgAdmin 4/venv/Lib/site-packages\alembic\script\base.py", line 427, in run_env

    util.load_python_file(self.dir, 'env.py')

  File "C:/Program Files/PostgreSQL/10/pgAdmin 4/venv/Lib/site-packages\alembic\util\pyfiles.py", line 81, in load_python_file

    module = load_module_py(module_id, path)

  File "C:/Program Files/PostgreSQL/10/pgAdmin 4/venv/Lib/site-packages\alembic\util\compat.py", line 135, in load_module_py

    mod = imp.load_source(module_id, path, fp)

  File "C:\Program Files\PostgreSQL\10\pgAdmin 4\web\pgadmin\setup\..\..\migrations\env.py", line 94, in <module>

    run_migrations_online()

  File "C:\Program Files\PostgreSQL\10\pgAdmin 4\web\pgadmin\setup\..\..\migrations\env.py", line 87, in run_migrations_online

    context.run_migrations()

  File "<string>", line 8, in run_migrations

  File "C:/Program Files/PostgreSQL/10/pgAdmin 4/venv/Lib/site-packages\alembic\runtime\environment.py", line 836, in run_migrations

    self.get_context().run_migrations(**kw)

  File "C:/Program Files/PostgreSQL/10/pgAdmin 4/venv/Lib/site-packages\alembic\runtime\migration.py", line 330, in run_migrations

    step.migration_fn(**kw)

  File "C:\Program Files\PostgreSQL\10\pgAdmin 4\web\migrations\versions\02b9dccdcfcb_.py", line 28, in upgrade

    'ALTER TABLE server ADD COLUMN bgcolor TEXT(10)'

  File "C:/Program Files/PostgreSQL/10/pgAdmin 4/venv/Lib/site-packages\sqlalchemy\engine\base.py", line 2075, in execute

    return connection.execute(statement, *multiparams, **params)

  File "C:/Program Files/PostgreSQL/10/pgAdmin 4/venv/Lib/site-packages\sqlalchemy\engine\base.py", line 942, in execute

    return self._execute_text(object, multiparams, params)

  File "C:/Program Files/PostgreSQL/10/pgAdmin 4/venv/Lib/site-packages\sqlalchemy\engine\base.py", line 1104, in _execute_text

    statement, parameters

  File "C:/Program Files/PostgreSQL/10/pgAdmin 4/venv/Lib/site-packages\sqlalchemy\engine\base.py", line 1200, in _execute_context

    context)

  File "C:/Program Files/PostgreSQL/10/pgAdmin 4/venv/Lib/site-packages\sqlalchemy\engine\base.py", line 1413, in _handle_dbapi_exception

    exc_info

  File "C:/Program Files/PostgreSQL/10/pgAdmin 4/venv/Lib/site-packages\sqlalchemy\util\compat.py", line 265, in raise_from_cause

    reraise(type(exception), exception, tb=exc_tb, cause=cause)

  File "C:/Program Files/PostgreSQL/10/pgAdmin 4/venv/Lib/site-packages\sqlalchemy\engine\base.py", line 1193, in _execute_context

    context)

  File "C:/Program Files/PostgreSQL/10/pgAdmin 4/venv/Lib/site-packages\sqlalchemy\engine\default.py", line 509, in do_execute

    cursor.execute(statement, parameters)

sqlalchemy.exc.OperationalError: (sqlite3.OperationalError) duplicate column name: bgcolor [SQL: 'ALTER TABLE server ADD COLUMN bgcolor TEXT(10)'] (Background on this error at: http://sqlalche.me/e/e3q8)

Exception KeyError: KeyError(15440,) in <module 'threading' from 'C:/Program Files/PostgreSQL/10/pgAdmin 4/venv\lib\threading.py'> ignored