Fixed #29713 -- Added check that LANGUAGE_CODE uses standard language id format.

3 files changed, 27 insertions, 0 deletions

diff --git a/django/core/checks/__init__.py b/django/core/checks/__init__.py
index 8ef3f5db90..ededae38ba 100644
--- a/django/core/checks/__init__.py
+++ b/django/core/checks/__init__.py
@@ -12,6 +12,7 @@ import django.core.checks.security.base  # NOQA isort:skip
 import django.core.checks.security.csrf  # NOQA isort:skip
 import django.core.checks.security.sessions  # NOQA isort:skip
 import django.core.checks.templates  # NOQA isort:skip
+import django.core.checks.translation  # NOQA isort:skip
 import django.core.checks.urls  # NOQA isort:skip
 
 
diff --git a/django/core/checks/registry.py b/django/core/checks/registry.py
index 9660272d9b..51999bdf95 100644
--- a/django/core/checks/registry.py
+++ b/django/core/checks/registry.py
@@ -15,6 +15,7 @@ class Tags:
     security = 'security'
     signals = 'signals'
     templates = 'templates'
+    translation = 'translation'
     urls = 'urls'
 
 
diff --git a/django/core/checks/translation.py b/django/core/checks/translation.py
new file mode 100644
index 0000000000..5c183aad2d
--- /dev/null
+++ b/django/core/checks/translation.py
@@ -0,0 +1,25 @@
+import re
+
+from django.conf import settings
+from django.utils.translation.trans_real import language_code_re
+
+from . import Error, Tags, register
+
+
+@register(Tags.translation)
+def check_setting_language_code(app_configs, **kwargs):
+    """
+    Errors if language code is in the wrong format. Language codes specification outlined by
+    https://en.wikipedia.org/wiki/IETF_language_tag#Syntax_of_language_tags
+    """
+    match_result = re.match(language_code_re, settings.LANGUAGE_CODE)
+    errors = []
+    if not match_result:
+        errors.append(Error(
+            "LANGUAGE_CODE in settings.py is {}. It should be in the form ll or ll-cc where ll is the language and cc "
+            "is the country. Examples include: it, de-at, es, pt-br. The full set of language codes specifications is "
+            "outlined by https://en.wikipedia.org/wiki/IETF_language_tag#Syntax_of_language_tags".format(
+                settings.LANGUAGE_CODE),
+            id="translation.E001",
+        ))
+    return errors