# Migrating Mojo Libraries from 25.7 to 26.1

**URL:** <https://forum.modular.com/t/migrating-mojo-libraries-from-25-7-to-26-1/2670>\
**Category:** Community Showcase\
**Created:** [February 2, 2026, 5:03am UTC](https://forum.modular.com/t/migrating-mojo-libraries-from-25-7-to-26-1/2670 "2026-02-02T05:03:47Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![mjboothaus](https://avatars.discourse-cdn.com/v4/letter/m/d07c76/32.png) [@mjboothaus](https://forum.modular.com/u/mjboothaus)\
**Post date:** [February 2, 2026, 5:03am UTC](https://forum.modular.com/t/migrating-mojo-libraries-from-25-7-to-26-1/2670/1 "2026-02-02T05:03:47Z")

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Just in time for the February 2026 Community meeting 😉 I’ve just finished migrating five open-source Mojo libraries from 0.25.7 to 0.26.1:

- [mojo-asciichart](https://github.com/databooth/mojo-asciichart)
- [mojo-dotenv](https://github.com/databooth/mojo-dotenv)
- [mojo-ini](https://github.com/databooth/mojo-ini)
- [mojo-toml](https://github.com/databooth/mojo-toml)
- [mojo-yaml](https://github.com/databooth/mojo-yaml)

They’re all “plain and simple Mojo” libraries (no MAX usage), but they do rely on the same underlying toolchain and channels, so the 0.26.1 release still meant a fair bit of work.

I wrote up a detailed article here:

👉 [Migrating Mojo Libraries from 25.7 to 26.1 🔥: Lessons from updating my mojo-packages](https://www.databooth.com.au/posts/mojo/migrating-mojo-libraries-to-26-1/)

The post covers:

- How I standardised toolchain versions across all projects (`max = ">=26.1.0,<27"` and `mojo_version = "=0.26.1"` in the recipes)
- What changed around string/indexing semantics and how I moved lexers and parsers over to `codepoint_slices()` and explicit `List[String]` buffers
- Why I’m aiming for “zero compiler warnings” on 26.1 to make future upgrades easier
- How I wired the pixi + pre-submit workflow to run all Mojo tests, examples, recipe validation, rattler-build, and a basic install smoke test
- A few case studies (mojo-dotenv, mojo-ini, mojo-toml, mojo-asciichart) and some benchmark before/after numbers

If you’re maintaining your own Mojo libraries or playing with text-heavy code in 26.1, I’d be interested in what you’re running into and whether there are better patterns we can share around string handling, error reporting, or benchmarking.

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**Author:** ![clattner](https://sea1.discourse-cdn.com/flex001/user_avatar/forum.modular.com/clattner/32/201_2.png) [@clattner](https://forum.modular.com/u/clattner)\
**Post date:** [February 2, 2026, 7:12am UTC](https://forum.modular.com/t/migrating-mojo-libraries-from-25-7-to-26-1/2670/2 "2026-02-02T07:12:23Z")

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Great summary, thank you for sharing this Michael. This is very helpful to understand the aggregate impact of changes being made to the language and libraries.

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**Author:** ![system](https://us1.discourse-cdn.com/flex001/uploads/modular/original/1X/2751e0fbdc595a99718b216730957e9db4448cfd.jpeg) [@system](https://forum.modular.com/u/system)\
**Post date:** [August 1, 2026, 7:13am UTC](https://forum.modular.com/t/migrating-mojo-libraries-from-25-7-to-26-1/2670/3 "2026-08-01T07:13:27Z")

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