django.db.utils.DatabaseError: ORA-12541: TNS:no listener

Tony007

hi am trying to connect to my database am geting this error my database is up and listner

python manage.py runserver

Watching for file changes with StatReloader

Performing system checks...

System check identified no issues (0 silenced).

Exception in thread django-main-thread:

Traceback (most recent call last):

 File "/home/django/Documents/pythonreact/ReactProj/django-backend/.venv/lib/python3.6/site-packages/django/db/backends/base/base.py", line 219, in ensure_connection

 self.connect()

 File "/home/django/Documents/pythonreact/ReactProj/django-backend/.venv/lib/python3.6/site-packages/django/utils/asyncio.py", line 26, in inner

 return func(*args, **kwargs)

 File "/home/django/Documents/pythonreact/ReactProj/django-backend/.venv/lib/python3.6/site-packages/django/db/backends/base/base.py", line 200, in connect

 self.connection = self.get_new_connection(conn_params)

 File "/home/django/Documents/pythonreact/ReactProj/django-backend/.venv/lib/python3.6/site-packages/django/utils/asyncio.py", line 26, in inner

 return func(*args, **kwargs)

 File "/home/django/Documents/pythonreact/ReactProj/django-backend/.venv/lib/python3.6/site-packages/django/db/backends/oracle/base.py", line 233, in get_new_connection

 **conn_params,

cx_Oracle.DatabaseError: ORA-12541: TNS:no listener

The above exception was the direct cause of the following exception:

Traceback (most recent call last):

 File "/usr/lib/python3.6/threading.py", line 916, in _bootstrap_inner

 self.run()

 File "/usr/lib/python3.6/threading.py", line 864, in run

 self._target(*self._args, **self._kwargs)

 File "/home/django/Documents/pythonreact/ReactProj/django-backend/.venv/lib/python3.6/site-packages/django/utils/autoreload.py", line 64, in wrapper

 fn(*args, **kwargs)

 File "/home/django/Documents/pythonreact/ReactProj/django-backend/.venv/lib/python3.6/site-packages/django/core/management/commands/runserver.py", line 121, in inner_run

 self.check_migrations()

 File "/home/django/Documents/pythonreact/ReactProj/django-backend/.venv/lib/python3.6/site-packages/django/core/management/base.py", line 486, in check_migrations

 executor = MigrationExecutor(connections[DEFAULT_DB_ALIAS])

 File "/home/django/Documents/pythonreact/ReactProj/django-backend/.venv/lib/python3.6/site-packages/django/db/migrations/executor.py", line 18, in __init__

 self.loader = MigrationLoader(self.connection)

 File "/home/django/Documents/pythonreact/ReactProj/django-backend/.venv/lib/python3.6/site-packages/django/db/migrations/loader.py", line 53, in __init__

 self.build_graph()

 File "/home/django/Documents/pythonreact/ReactProj/django-backend/.venv/lib/python3.6/site-packages/django/db/migrations/loader.py", line 220, in build_graph

 self.applied_migrations = recorder.applied_migrations()

 File "/home/django/Documents/pythonreact/ReactProj/django-backend/.venv/lib/python3.6/site-packages/django/db/migrations/recorder.py", line 77, in applied_migrations

 if self.has_table():

 File "/home/django/Documents/pythonreact/ReactProj/django-backend/.venv/lib/python3.6/site-packages/django/db/migrations/recorder.py", line 55, in has_table

 with self.connection.cursor() as cursor:

 File "/home/django/Documents/pythonreact/ReactProj/django-backend/.venv/lib/python3.6/site-packages/django/utils/asyncio.py", line 26, in inner

 return func(*args, **kwargs)

 File "/home/django/Documents/pythonreact/ReactProj/django-backend/.venv/lib/python3.6/site-packages/django/db/backends/base/base.py", line 259, in cursor

 return self._cursor()

 File "/home/django/Documents/pythonreact/ReactProj/django-backend/.venv/lib/python3.6/site-packages/django/db/backends/base/base.py", line 235, in _cursor

 self.ensure_connection()

 File "/home/django/Documents/pythonreact/ReactProj/django-backend/.venv/lib/python3.6/site-packages/django/utils/asyncio.py", line 26, in inner

 return func(*args, **kwargs)

 File "/home/django/Documents/pythonreact/ReactProj/django-backend/.venv/lib/python3.6/site-packages/django/db/backends/base/base.py", line 219, in ensure_connection

 self.connect()

 File "/home/django/Documents/pythonreact/ReactProj/django-backend/.venv/lib/python3.6/site-packages/django/db/utils.py", line 90, in __exit__

 raise dj_exc_value.with_traceback(traceback) from exc_value

 File "/home/django/Documents/pythonreact/ReactProj/django-backend/.venv/lib/python3.6/site-packages/django/db/backends/base/base.py", line 219, in ensure_connection

 self.connect()

 File "/home/django/Documents/pythonreact/ReactProj/django-backend/.venv/lib/python3.6/site-packages/django/utils/asyncio.py", line 26, in inner

 return func(*args, **kwargs)

 File "/home/django/Documents/pythonreact/ReactProj/django-backend/.venv/lib/python3.6/site-packages/django/db/backends/base/base.py", line 200, in connect

 self.connection = self.get_new_connection(conn_params)

 File "/home/django/Documents/pythonreact/ReactProj/django-backend/.venv/lib/python3.6/site-packages/django/utils/asyncio.py", line 26, in inner

 return func(*args, **kwargs)

 File "/home/django/Documents/pythonreact/ReactProj/django-backend/.venv/lib/python3.6/site-packages/django/db/backends/oracle/base.py", line 233, in get_new_connection

 **conn_params,

django.db.utils.DatabaseError: ORA-12541: TNS:no listener

my server listner

status

Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=199.777.7.111)(PORT=1539)))

STATUS of the LISTENER

------------------------

Alias      LISTENER

Version     TNSLSNR for Linux: Version 19.0.0.0.0 - Production

Start Date    09-JUL-2021 07:04:29

Uptime     2 days 1 hr. 2 min. 29 sec

Trace Level    off

Security     ON: Local OS Authentication

SNMP      OFF

Listener Parameter File /u1/app/oracle/product/19.0.0/dbhome_1/network/admin/listener.ora

Listener Log File   /u1/app/oracle/product/19.0.0/dbhome_1/network/log/listener.log

Listening Endpoints Summary...

 (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=199.777.7.111)(PORT=1539)))

 (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=EXTPROC1521)))

 (DESCRIPTION=(ADDRESS=(PROTOCOL=tcps)(HOST=hostname)(PORT=5500))(Security=(my_wallet_directory=/u1/app/oracle/admin/dbname/xdb_wallet))(Presentation=HTTP)(Session=RAW))

 (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=hostname)(PORT=8081))(Presentation=HTTP)(Session=RAW))

Services Summary...

Service "dbname" has 2 instance(s).

 Instance "dbname", status UNKNOWN, has 1 handler(s) for this service...

 Instance "dbname", status READY, has 1 handler(s) for this service...

Service "ncsalphaXDB" has 1 instance(s).

 Instance "dbname", status READY, has 1 handler(s) for this service...

The command completed successfully

LSNRCTL> status

Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=199.777.7.111)(PORT=1539)))

STATUS of the LISTENER

------------------------

Alias      LISTENER

Version     TNSLSNR for Linux: Version 19.0.0.0.0 - Production

Start Date    09-JUL-2021 07:04:29

Uptime     2 days 1 hr. 2 min. 56 sec

Trace Level    off

Security     ON: Local OS Authentication

SNMP      OFF

Listener Parameter File /u1/app/oracle/product/19.0.0/dbhome_1/network/admin/listener.ora

Listener Log File   /u1/app/oracle/product/19.0.0/dbhome_1/network/log/listener.log

Listening Endpoints Summary...

 (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=199.777.7.111)(PORT=1539)))

 (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=EXTPROC1521)))

 (DESCRIPTION=(ADDRESS=(PROTOCOL=tcps)(HOST=hostname)(PORT=5500))(Security=(my_wallet_directory=/u1/app/oracle/admin/dbname/xdb_wallet))(Presentation=HTTP)(Session=RAW))

 (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=hostname)(PORT=8081))(Presentation=HTTP)(Session=RAW))

Services Summary...

Service "dbname" has 2 instance(s).

 Instance "dbname", status UNKNOWN, has 1 handler(s) for this service...

 Instance "dbname", status READY, has 1 handler(s) for this service...

Service "dbnameXDB" has 1 instance(s).

 Instance "dbname", status READY, has 1 handler(s) for this service...

The command completed successfully

LSNRCTL> service

Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=199.777.7.111)(PORT=1539)))

Services Summary...

Service "dbname" has 2 instance(s).

 Instance "dbname", status UNKNOWN, has 1 handler(s) for this service...

 Handler(s):

  "DEDICATED" established:0 refused:0

   LOCAL SERVER

 Instance "dbname", status READY, has 1 handler(s) for this service...

 Handler(s):

  "DEDICATED" established:275 refused:0 state:ready

   LOCAL SERVER

Service "ncsalphaXDB" has 1 instance(s).

 Instance "dbname", status READY, has 1 handler(s) for this service...

 Handler(s):

  "D000" established:0 refused:0 current:0 max:1022 state:ready

   DISPATCHER <machine: hostname, pid: 2679>

   (ADDRESS=(PROTOCOL=tcp)(HOST=hostname)(PORT=25278))

The command completed successfully

LSNRCTL> !

NL-00853: undefined command "!". Try "help"

LSNRCTL> exit

[[email protected] ~]$ cat /etc/hosts

127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4

::1   localhost localhost.localdomain localhost6 localhost6.localdomain6

199.777.7.111 hostname

Christopher Jones-Oracle

Start by checking that SQL*Plus (not SQL Developer) can connect.

Then try a Python program that calls cx_Oracle directly (not using Django).

This post has some useful tips that apply to all apps connecting to a remote DB: https://www.thatjeffsmith.com/archive/2014/09/ora-12545-12541-12514-01017/

Roland Mueller

Before running Django app you should of course check

• whether the listener is up & running in DB machine
• whether you can connect from host where django app is running to DB server+DB port. DB port is 1521 by default, but in the text I saw 1539 mentioned
• connection check can be done using nmap or simply the telnet client app: 'telnet DB_HOST PORT'

Shouldn't connecting to Oracle DB using the default port 1521 in this way in settings.py?

• variables DB_HOSTNAME and SID_OR_SERVICE are set in same settings.py

'default': {

        'ENGINE': 'django.db.backends.oracle',

        'NAME': DB_HOSTNAME + ':1521/' + SID_OR_SERVICE,

        'USER': 'user',

        'PASSWORD': 'pass',

    }

With other port 1521 has to be replaced.

Christopher Jones-Oracle

One note: 'SID_OR_SERVICE' should be 'SERVICE' since the 'easy connect' syntax doesn't support SIDs.

A couple of recent blog posts might be of interest:

https://blogs.oracle.com/opal/connecting-to-oracle-cloud-autonomous-database-with-django

https://blogs.oracle.com/opal/running-oracle-database-backed-django-web-applications-on-apache

Tony007

this my setting

"""

Django settings for mysite project.

Generated by 'django-admin startproject' using Django 2.0.2.

For more information on this file, see

https://docs.djangoproject.com/en/2.0/topics/settings/

For the full list of settings and their values, see

https://docs.djangoproject.com/en/2.0/ref/settings/

"""

import os

# Build paths inside the project like this: os.path.join(BASE_DIR, ...)

BASE_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))

# Quick-start development settings - unsuitable for production

# See https://docs.djangoproject.com/en/2.0/howto/deployment/checklist/

# SECURITY WARNING: keep the secret key used in production secret!

SECRET_KEY = '39tl#ywdu(^i#u2f-rosga7vn)&uchp^h96myvl4wo80a=+4g*'

# SECURITY WARNING: don't run with debug turned on in production!

DEBUG = True

ALLOWED_HOSTS = []

# Application definition

INSTALLED_APPS = [

  'django.contrib.admin',

  'django.contrib.auth',

  'django.contrib.contenttypes',

  'django.contrib.sessions',

  'django.contrib.messages',

  'django.contrib.staticfiles',

  'accounts',

  'oauth2_provider',

  'rest_framework',

]

MIDDLEWARE = [

  'corsheaders.middleware.CorsMiddleware',

  'corsheaders.middleware.CorsPostCsrfMiddleware',

  'django.middleware.security.SecurityMiddleware',

  'django.contrib.sessions.middleware.SessionMiddleware',

  'django.middleware.common.CommonMiddleware',

  'django.middleware.csrf.CsrfViewMiddleware',

  'django.contrib.auth.middleware.AuthenticationMiddleware',

  'django.contrib.messages.middleware.MessageMiddleware',

  'django.middleware.clickjacking.XFrameOptionsMiddleware',

]

ROOT_URLCONF = 'mysite.urls'

TEMPLATES = [

  {

    'BACKEND': 'django.template.backends.django.DjangoTemplates',

    'DIRS': [],

    'APP_DIRS': True,

    'OPTIONS': {

      'context_processors': [

        'django.template.context_processors.debug',

        'django.template.context_processors.request',

        'django.contrib.auth.context_processors.auth',

        'django.contrib.messages.context_processors.messages',

      ],

    },

  },

]

WSGI_APPLICATION = 'mysite.wsgi.application'

# Database

# https://docs.djangoproject.com/en/2.0/ref/settings/#databases

DATABASES = {

  'default': {

    'ENGINE': 'django.db.backends.oracle',

    'NAME': 'dbname',

    'USER': 'username',

    'PASSWORD': 'password',

    'PORT': '1539',

    'HOST': '199.154.7.188'

  }

}

# Password validation

# https://docs.djangoproject.com/en/2.0/ref/settings/#auth-password-validators

AUTH_PASSWORD_VALIDATORS = [

  {

    'NAME': 'django.contrib.auth.password_validation.UserAttributeSimilarityValidator',

  },

  {

    'NAME': 'django.contrib.auth.password_validation.MinimumLengthValidator',

  },

  {

    'NAME': 'django.contrib.auth.password_validation.CommonPasswordValidator',

  },

  {

    'NAME': 'django.contrib.auth.password_validation.NumericPasswordValidator',

  },

]

# Internationalization

# https://docs.djangoproject.com/en/2.0/topics/i18n/

LANGUAGE_CODE = 'en-us'

TIME_ZONE = 'UTC'

USE_I18N = True

USE_L10N = True

USE_TZ = True

# Static files (CSS, JavaScript, Images)

# https://docs.djangoproject.com/en/2.0/howto/static-files/

STATIC_URL = '/static/'

AUTH_USER_MODEL = 'accounts.User'

CORS_ORIGIN_ALLOW_ALL = True

OAUTH2_PROVIDER = {

  # this is the list of available scopes

  'SCOPES': {'read': 'Read scope', 'write': 'Write scope', 'groups': 'Access to your groups'}

}

REST_FRAMEWORK = {

  # Use Django's standard `django.contrib.auth` permissions,

  # or allow read-only access for unauthenticated users.

  'DEFAULT_AUTHENTICATION_CLASSES': (

    'rest_framework.authentication.BasicAuthentication',

    'rest_framework.authentication.SessionAuthentication',

    'oauth2_provider.contrib.rest_framework.OAuth2Authentication',

  )

}

 telnet 199.128.2.111:1539

telnet: could not resolve 192.168.8.123:1539/telnet: Name or service not known

Christopher Jones-Oracle

If you are having network issues, install SQL*Plus (not SQL Developer) on the machine where you run Python and make sure you can connect to the database using that. Then the same connection string will be usable in Django (assuming it runs in the same environment)