app.use('/prefix', fn) strips query strings from req.url since v9.2.0

[panva]

Prerequisites

• I have written a descriptive issue title
• I have searched existing issues to ensure the bug has not already been reported

Fastify version

5.7.4

Plugin version

9.2.0

Node.js version

24.13.1

Operating system

macOS

Operating system version (i.e. 20.04, 11.3, 10)

26.3

Description

Since v9.2.0, when middleware is registered with a path prefix via app.use('/prefix', fn), the query string is stripped from req.url before it reaches the middleware.

For example, a request to /api/resource?foo=bar&baz=qux results in the middleware receiving req.url as /resource instead of /resource?foo=bar&baz=qux.

This was not the case in v9.1.0.

Link to code that reproduces the bug

https://gist.github.com/panva/dd9197ce97d7daffc0ad341b5516d192

Expected Behavior

req.url in the middleware should be /resource?foo=bar&baz=qux — with the prefix stripped but the query string preserved.

Actual behavior: req.url is /resource — query string is lost.

[ghostd]

Hi,

Thanks for the fix. Is there something blocking the release ?