Exceptions Reference

All django-sysconfig exceptions inherit from ConfigError, so you can catch them at any granularity you need.

from django_sysconfig.exceptions import (
    ConfigError,
    InvalidPathError,
    AppNotFoundError,
    FieldNotFoundError,
    ConfigValidationError,
    ConfigValueError,
)

---

Exception hierarchy

ConfigError
├── InvalidPathError
├── AppNotFoundError
├── FieldNotFoundError
├── ConfigValidationError
└── ConfigValueError

---

ConfigError

Base class for all django-sysconfig exceptions. Catch this to handle any config-related exception in one place.

from django_sysconfig.exceptions import ConfigError

try:
    value = config.get("some.path.here")
except ConfigError as e:
    # Something went wrong — path invalid, app not found, field not found, etc.
    value = "fallback"

---

InvalidPathError

Raised when the path passed to any accessor method doesn't have exactly three dot-separated parts.

Triggers:

• config.get("myapp.site_name") — only two parts
• config.get("myapp.general.site.name") — four parts
• config.get("") — empty string
• config.get("myapp") — one part

from django_sysconfig.exceptions import InvalidPathError

try:
    config.get("myapp.general")  # missing field segment
except InvalidPathError as e:
    print(e)  # "Path must have exactly three dot-separated parts: 'myapp.general'"

---

AppNotFoundError

Raised when the first segment of the path (the app label) has no registered configuration. This usually means there's no sysconfig.py file in that app, or the file doesn't use @register_config(...), or the app isn't in INSTALLED_APPS.

Triggers:

• config.get("nonexistent_app.general.field")
• config.set("nonexistent_app.general.field", "value")

from django_sysconfig.exceptions import AppNotFoundError

try:
    config.get("typo_in_appname.general.site_name")
except AppNotFoundError as e:
    print(e)  # "No config registered for app: 'typo_in_appname'"

Common cause: You defined a sysconfig.py but the app isn't in INSTALLED_APPS, so it was never autodiscovered.

---

FieldNotFoundError

Raised when the app is registered but the section or field doesn't exist in the schema.

Triggers:

• config.get("myapp.general.nonexistent_field") — field doesn't exist
• config.get("myapp.nonexistent_section.field") — section doesn't exist

from django_sysconfig.exceptions import FieldNotFoundError

try:
    config.get("myapp.general.old_field_name")  # field was renamed
except FieldNotFoundError as e:
    print(e)  # "Field not found: 'myapp.general.old_field_name'"

Common cause: A field was renamed or removed from the schema, but the old path is still referenced somewhere in the codebase.

---

ConfigValidationError

Raised when a value fails one or more field validators. The write is aborted and nothing is saved.

Triggers:

• config.set("myapp.general.max_items", -1) — if a PositiveValidator is on the field
• config.set("notifications.email.sender", "not-an-email") — if EmailValidator is on the field

from django_sysconfig.exceptions import ConfigValidationError

try:
    config.set("myapp.general.max_items", -5)
except ConfigValidationError as e:
    print(e.errors)  # ["Max Items Per User: Value must be greater than zero."]

e.errors is a list of all validation error strings — all validators run even if an earlier one fails, so the user sees every issue at once.

---

ConfigValueError

Raised when a value can't be serialized for the given field type (not a validation failure — a type error).

Triggers:

• config.set("myapp.general.max_items", "not-a-number") — wrong type for IntegerFrontendModel

from django_sysconfig.exceptions import ConfigValueError

try:
    config.set("myapp.general.max_items", object())
except ConfigValueError as e:
    print(e)