Autoredirect to 404 when custom page url is used

[cristaloleg]

🐛 Bug Report

Prerequisites

• I'm using the latest version of Docusaurus.
• I have tried the npm run clear or yarn clear command.
• I have tried rm -rf node_modules yarn.lock package-lock.json and re-installing packages.
• I have tried creating a repro with https://new.docusaurus.io
• I have read the console error message carefully (if applicable)

Description

I have deployed Docusaurus at Cloudflare Pages (see https://flyer-flutter-docs.pages.dev/chat-ui/installation) and everything is fine. However, I also have tried to use it on our own domain with a simple redirection (via Cloudflare Workers, that's not so important) https://docs.flyer.chat/flutter/chat-ui/installation But sadly Docusaurus redirects me to 404.

Have you read the Contributing Guidelines on issues?

Yes.

Steps to reproduce

Use https://new.docusaurus.io to create a CodeSandbox reproducible demo of the bug.

(Write your steps here:)

1. Open https://flyer-flutter-docs.pages.dev/chat-ui/installation - everything is fine
2. Open https://docs.flyer.chat/flutter/chat-ui/installation - correct pages is opened and then redirection to 404 page.

Expected behavior

Expecting the same behaviour at https://flyer-flutter-docs.pages.dev/chat-ui/installation as at https://docs.flyer.chat/flutter/chat-ui/installation

Actual behavior

The returned page is correct, but then it redirects to 404 page. It's easy to see this redirect, just smash cmd+R to refresh the page.

Your environment

• Public source code: not yet
• Public site URL: https://flyer-flutter-docs.pages.dev/chat-ui/installation
• Docusaurus version used: 2.0.0-beta.6
• Environment name and version (e.g. Chrome 78.0.3904.108, Node.js 10.17.0): Chrome 92.0.4515.159
• Operating system and version (e.g. Ubuntu 20.04.2 LTS): macOS 10.15.6

Reproducible demo

Links are already mentioned above.

Note

Problem occurs with every page, chat-ui/installation is just the smallest page in our docs.

[cristaloleg]

Part of docusaurus.config.js, everything else looks not so important.

module.exports = {
  title: 'Flyer Chat',
  tagline: 'Flyer Chat is a platform for creating in-app chat experiences using Flutter or React Native.',
  url: 'https://docs.flyer.chat',
  baseUrl: '/flutter',
  onBrokenLinks: 'throw',
  onBrokenMarkdownLinks: 'warn',
  favicon: 'img/favicon.ico',
  organizationName: 'flyerhq',
  projectName: 'flutter-flyer-chat'
  ...

[lex111]

Does baseUrl field in config file of your site on custom domain contain trailing slash ('/flutter' -> '/flutter/')? Check whether this issue is reproduced on your local dev server?

[cristaloleg]

Nice, my bad, have missed that build failed due to Error: "baseUrl" must be a string with a trailing slash.

https://docs.flyer.chat/flutter/chat-ui/installation already works fine
but https://flyer-flutter-docs.pages.dev/flutter/chat-ui/ is broken 'cause there is no /flutter prefix for assets, it's a separate problem and can be left as it is.

Thanks @lex111