# What changed in xlsxwriter

> 14 changes in xlsxwriter 1 to 3 from its official release notes, upgrade guides and advisories: 3 breaking, 8 new APIs and options. Each one cited. Sources checked 2026-10-25. HTML: https://unstale.sh/pypi/xlsxwriter/

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

## xlsxwriter 3

### Breaking changes

- Priorities now follow the order in which rules were added when a cell range is repeated after a different range. (3.3.0) — [release notes](https://github.com/jmcnamara/XlsxWriter/blob/6c09d7586d2162368f46a6ae45ac2882de6eb1d2/Changes#release-330---october-22-2026)
- An unsupported source type now raises TypeError instead of ValueError. (3.3.0) — [release notes](https://github.com/jmcnamara/XlsxWriter/blob/6c09d7586d2162368f46a6ae45ac2882de6eb1d2/Changes#release-330---october-22-2026)
- An unsupported theme type now raises TypeError instead of ValueError. (3.3.0) — [release notes](https://github.com/jmcnamara/XlsxWriter/blob/6c09d7586d2162368f46a6ae45ac2882de6eb1d2/Changes#release-330---october-22-2026)

### New APIs and options

- Adds a chartsheet method that automatically fits the sheet to the screen, including when the window is resized. (3.3.0) — [release notes](https://github.com/jmcnamara/XlsxWriter/blob/6c09d7586d2162368f46a6ae45ac2882de6eb1d2/Changes#release-330---october-22-2026)
- Adds a method to set the default workbook theme from a user-supplied .thmx, .xlsx, or theme1.xml file. (3.3.0) — [release notes](https://github.com/jmcnamara/XlsxWriter/blob/6c09d7586d2162368f46a6ae45ac2882de6eb1d2/Changes#release-330---october-22-2026)
- Adds a constructor option to change the default font and cell size to match the theme. (3.3.0) — [release notes](https://github.com/jmcnamara/XlsxWriter/blob/6c09d7586d2162368f46a6ae45ac2882de6eb1d2/Changes#release-330---october-22-2026)
- Adds a constructor option to change the default font and cell size to match the theme. (3.3.0) — [release notes](https://github.com/jmcnamara/XlsxWriter/blob/6c09d7586d2162368f46a6ae45ac2882de6eb1d2/Changes#release-330---october-22-2026)
- Adds a constructor option to change the default font and cell size to match the theme. (3.3.0) — [release notes](https://github.com/jmcnamara/XlsxWriter/blob/6c09d7586d2162368f46a6ae45ac2882de6eb1d2/Changes#release-330---october-22-2026)
- Adds the description option for worksheet Table alt text. (3.3.0) — [release notes](https://github.com/jmcnamara/XlsxWriter/blob/6c09d7586d2162368f46a6ae45ac2882de6eb1d2/Changes#release-330---october-22-2026)
- Adds the title option for worksheet Table alt text. (3.3.0) — [release notes](https://github.com/jmcnamara/XlsxWriter/blob/6c09d7586d2162368f46a6ae45ac2882de6eb1d2/Changes#release-330---october-22-2026)

### Fixes and other changes

- Checks that the range is within worksheet limits, preventing corrupt files for large worksheets. (3.3.0) — [release notes](https://github.com/jmcnamara/XlsxWriter/blob/6c09d7586d2162368f46a6ae45ac2882de6eb1d2/Changes#release-330---october-22-2026)
- Prevents a spurious Invalid cell reference warning when a chart series uses a defined name with a sheet reference. (3.3.0) — [release notes](https://github.com/jmcnamara/XlsxWriter/blob/6c09d7586d2162368f46a6ae45ac2882de6eb1d2/Changes#release-330---october-22-2026)
- Fixes width and height detection for large GIF and top-down BMP images, and adds dimension validation. (3.3.0) — [release notes](https://github.com/jmcnamara/XlsxWriter/blob/6c09d7586d2162368f46a6ae45ac2882de6eb1d2/Changes#release-330---october-22-2026)

## xlsxwriter 1

### New APIs and options

- Icon sets were added to conditional formatting, allowing developers to use them in conditional formats. (1.0.0) — [release notes](https://github.com/jmcnamara/XlsxWriter/blob/HEAD/Changes)