# What changed in configargparse

> 9 changes in configargparse 1 from its official release notes, upgrade guides and advisories: 3 breaking, 1 new APIs and options. Each one cited. Sources checked 2026-10-18. HTML: https://unstale.sh/pypi/configargparse/

To see which of these apply to a repository, run `npx @unstale/cli init` in it.

## configargparse 1

### Breaking changes

- Values from higher-priority sources now override conflicting values in mutually exclusive groups; conflicts within one source still raise an error. (1.8.0) — [release notes](https://github.com/bw2/ConfigArgParse/releases/tag/v1.8.0)
- A parser missing an optional dependency now raises this exception, a subclass of ConfigFileParserException, instead of being silently skipped. (1.7.7) — [release notes](https://github.com/bw2/ConfigArgParse/releases/tag/v1.7.7)
- Values containing newlines are rejected when writing out a config file, rather than being written out as separate keys. (1.7.6) — [release notes](https://github.com/bw2/ConfigArgParse/releases/tag/v1.7.6)

### New APIs and options

- The toml extra declares the optional dependency used for TOML support, including writing config files on every Python version. (1.7.7) — [release notes](https://github.com/bw2/ConfigArgParse/releases/tag/v1.7.7)

### Behavior and default changes

- CompositeConfigParser warns with the parser name and installation instructions, then continues down the parser chain. (1.7.7) — [release notes](https://github.com/bw2/ConfigArgParse/releases/tag/v1.7.7)
- TOML config files can now be read from binary streams on Python versions before 3.11. (1.7.7) — [release notes](https://github.com/bw2/ConfigArgParse/releases/tag/v1.7.7)

### Tooling

- Python 3.14 is now supported and tested in CI. (1.8.0) — [release notes](https://github.com/bw2/ConfigArgParse/releases/tag/v1.8.0)

### Fixes and other changes

- Arguments declared with a custom argparse Action and nargs can now be set from a config file. (1.7.7) — [release notes](https://github.com/bw2/ConfigArgParse/releases/tag/v1.7.7)
- Config file and environment variable values can no longer trigger writing out a config file. (1.7.6) — [release notes](https://github.com/bw2/ConfigArgParse/releases/tag/v1.7.6)