fix: correct precedence when building urlToUse in createLocalReq

[rubixvi]

This appears to be a new error produced with the latest update of next.

Occurs when front end is using a simple component for example to send a user to the payloadcms backend. This throws a new error. This only occurs with links to the /admin page.

[20:11:25] ERROR: Failed to create URL object from URL: http://localhost:3000http://localhost:3000/admin, falling back to http://localhost:3000http://localhost:3000/admin
⨯ TypeError: Invalid URL
    at ignore-listed frames {
  code: 'ERR_INVALID_URL',
  input: 'http://localhost:3000http://localhost:3000/admin',
  digest: '1079054744'
}

node_modules\.pnpm\@payloadcms+next@3.68.3_@ty_5c4107aa334225014c648de0038e6397\node_modules\@payloadcms\next\src\utilities\initReq.ts (103:25) @ <anonymous> 101 | const { req: reqOverrides, ...optionsOverrides } = overrides || {} 102 | > 103 | const req = await createLocalReq( | ^ 104 | { 105 | req: { 106 | headers,

Fixes #14900

[Copilot]

Pull request overview

This PR fixes a bug where Next.js Link components pointing to /admin caused URL duplication errors (e.g., http://localhost:3000http://localhost:3000/admin). The issue stemmed from faulty conditional logic in URL construction that would use serverURL even when req.url was already set.

Key changes:

• Refactored the URL construction logic to properly prioritize req.url over serverURL
• Added trailing slash removal from serverURL to prevent malformed URLs
• Converted ternary expression to explicit if-else blocks for clearer URL selection logic

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[jacobsfletch]

Hey @rubixvi, this does prevent the admin panel itself from crashing, but I was able to produce the following url when navigating to the list view:

http://localhost:3000/http://localhost:3000/admin/collections/users?limit=10

Clearly this is wrong...we must not be relying on it anywhere else. This was definitely introduced in #14869, but the problem is related to the url suffix, not necessary how the url is constructed. As the name implies, the suffix shouldn't include the server url in the first place.

Your fix passes because the incorrect suffix happens to start with a leading slash:

/http://localhost:3000/admin/collections/users?limit=10

This allows us to construct a valid url object, albeit with an incorrect path. The problem is that serverURL is included in the suffix here via currentRoute:

payload/packages/next/src/views/Root/index.tsx

Line 141 in bb1501e

urlSuffix: `${currentRoute}${searchParams ? queryString : ''}`,

I also imagine your change might cause other issues too, for example req.url is no longer appended with the suffix.

[rubixvi]

@jacobsfletch I'll start a patch file and come back to this, just realise /dashboard and root /admin are affected at the moment.

I couldn't reproduce the error in list view.

[jacobsfletch]

Got a fix queued up here: #14907