Fixing configparser.NoSectionError in Python ConfigParser when moving to pathlib.Path for INI files

Learn why configparser.NoSectionError occurs after switching to pathlib.Path: create the missing section, store str(path), rebuild Path on read, safely.

When migrating from plain string paths to pathlib.Path, it’s easy to get blindsided by a configparser.NoSectionError and assume the problem is about Windows backslashes. It isn’t. The exception means you’re reading from or writing to a section that doesn’t exist in the configuration yet.

Problem recap

You read and write an INI config with ConfigParser. Paths used to be stored as str, then you switched to Path from pathlib. Suddenly you see configparser.NoSectionError: No section:. The timing makes it look like WindowsPath is to blame, but the root cause is elsewhere.

Minimal example that reproduces the error

from configparser import ConfigParser as IniCfg
from pathlib import Path as FsPath
ini = IniCfg()
# No section has been created yet.
# The next line raises configparser.NoSectionError
ini.set('Paths', 'file', str(FsPath(r'C:\Users\Example\File.txt')))
with open('config.ini', 'w') as out_fh:
    ini.write(out_fh)

What’s actually happening

configparser.NoSectionError is raised when set() or get() targets a section that doesn’t exist. It is not caused by using WindowsPath or by backslashes in the path string. The exception simply tells you the section hasn’t been added to the configuration yet.

Fix

Create the section before calling set() or get(), then write the string form of the Path to the file and reconstruct a Path when reading.

from configparser import ConfigParser as IniCfg
from pathlib import Path as FsPath
ini = IniCfg()
ini.add_section('Paths')
ini.set('Paths', 'file', str(FsPath(r'C:\Users\Example\File.txt')))
with open('config.ini', 'w') as out_fh:
    ini.write(out_fh)
ini.read('config.ini')
path_obj = FsPath(ini.get('Paths', 'file'))

Why this detail matters

Misdiagnosing the source of configparser.NoSectionError leads to chasing the wrong problem. Path handling on Windows is fine here; the failure is about missing configuration structure. If certain categories or sections are optional and may not be present based on user choices, this exception is the expected behavior whenever you try to interact with a non-existent section.

Takeaways

Ensure the section exists before using set() or get(). Store paths by writing str(path_obj) and reconstruct them with Path(...) on read. Understanding that NoSectionError signals an absent section—not a path formatting issue—keeps your configuration code predictable and prevents false alarms when working with Windows paths.