# Page Not Found

The URL `add-ons/tb68` does not exist.

You might be looking for one of these pages:
- [Update for Thunderbird 68](https://developer.thunderbird.net/add-ons/updating/tb68.md)
- [Update for Thunderbird 78](https://developer.thunderbird.net/add-ons/updating/tb78.md)
- [Update for Thunderbird 128](https://developer.thunderbird.net/add-ons/updating/tb128.md)
- [Add-on Update Guides](https://developer.thunderbird.net/add-ons/updating.md)
- [Update for Thunderbird 91](https://developer.thunderbird.net/add-ons/updating/tb91.md)

## How to find the correct page

1. **Browse the full index**: [/sitemap.md](https://developer.thunderbird.net/sitemap.md) - Complete documentation index
2. **View the full content**: [/llms-full.txt](https://developer.thunderbird.net/llms-full.txt) - Full content export

## Tips for requesting documentation

- For markdown responses, append `.md` to URLs (e.g., `/add-ons/updating/tb68.md`)
- Use `Accept: text/markdown` header for content negotiation