# Zen Browser 1.21.16b — Release build - 1.21.16b (2026-08-28)

- Product: Zen Browser (https://whatsnew.fyi/product/zen-browser)
- Vendor: Zen Browser
- Date: 2026-08-29
- Version: 1.21.16b
- Original notes: https://github.com/zen-browser/desktop/releases/tag/1.21.16b
- Permalink: https://whatsnew.fyi/product/zen-browser/releases/1.21.16b

What's New is an index, not a publisher: every entry below links to the vendor's own release notes, which are the authoritative source. Entries are labelled where they are hand-curated sample data, pre-releases, or drawn from a secondary source such as a developer blog.

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- **changed** — Update Firefox version to 154.0.1
- **fixed** — Improved session store performance, lowering CPU usage spikes and disk usage when storing the session
- **fixed** — Fixed duplicate separator on tab context menu
- **fixed** — Fixed minimizing PiP window failing to collapse into the sidebar
- **fixed** — Fixed slower access to saved passwords and unexpected Primary Password prompts caused by recent changes to password storage
- **fixed** — Fixed an issue where addresses were failing to autofill on some sites

#### Zen Stable Release


##### New Features
- Update Firefox version to 154.0.1

##### Fixes
- Improved on session store performance, lowering CPU usage spikes and disk usage when storing the session ([#14990](https://github.com/zen-browser/desktop/issues/14990))
- Fixed duplicate separator on tab context menu ([#15031](https://github.com/zen-browser/desktop/issues/15031))
- Fixed minimizing PiP window failing to collapse into the sidebar ([#14710](https://github.com/zen-browser/desktop/issues/14710))
- Fixed slower access to saved passwords and unexpected Primary Password prompts caused by recent changes to password storage.
- Fixed an issue where addresses were failing to autofill on some sites.
- Other bug fixes and improvements.