BUG #15156: The application server could not be contacted.

The following bug has been logged on the website:

Bug reference:      15156
Logged by:          Alonso Garcia Perez
Email address:      alo9083@yahoo.com.mx
PostgreSQL version: 10.3
Operating system:   Fedora 27
Description:

Traceback (most recent call last):
  File "/usr/lib/python3.6/site-packages/pgadmin4-web/pgAdmin4.py", line 34,
in <module>
    import config
  File "/usr/lib/python3.6/site-packages/pgadmin4-web/config.py", line 30,
in <module>
    from pgadmin.utils import env, IS_PY2, IS_WIN, fs_short_path
  File "/usr/lib/python3.6/site-packages/pgadmin4-web/pgadmin/__init__.py",
line 20, in <module>
    from flask_security import Security, SQLAlchemyUserDatastore,
current_user
  File
"/usr/lib/python3.6/site-packages/pgadmin4-web/flask_security/__init__.py",
line 13, in <module>
    from .core import Security, RoleMixin, UserMixin, AnonymousUser,
current_user
  File
"/usr/lib/python3.6/site-packages/pgadmin4-web/flask_security/core.py", line
18, in <module>
    from flask_babelex import Domain
ModuleNotFoundError: No module named 'flask_babelex'