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URLs with redundant slashes cause Unpoly to trigger a DOMException #612
Description
Bug description
While testing an application which was using Unpoly, I noticed that the Cookie Banner was somehow not working at all.
The culprit however was the JavaScript exception within Unpoly's source code:
Uncaught DOMException: Failed to execute 'replaceState' on 'History': A history state object with URL 'http://en/sign-in' cannot be created in a document with origin 'http://foobar.lvh.me:3000' and URL 'http://foobar.lvh.me:3000//en/sign-in'.
Due to a copy&paste mistake I was accessing the page at http://foobar.lvh.me:3000//en/sign-in' (two forward slashes) instead of http://foobar.lvh.me:3000/en/sign-in'. That's a niche case, but as the application renders fine in this case I'd except Unpoly not to crash too.
Steps to reproduce the behavior:
- Go to
https://unpoly.com//install - See the following error in the console:
Uncaught DOMException: Failed to execute 'replaceState' on 'History': A history state object with URL 'https://install/' cannot be created in a document with origin 'https://unpoly.com' and URL 'https://unpoly.com//install'.
Browser version
- OS: Linux
- Browser Chrome
- Version 124
Activity
adam12 commentedon May 8, 2024
Thanks for the report. I see the same on Safari + MacOS.
hiSandog commentedon Jun 29, 2026
Reproduced this at
https://unpoly.com//installtoo — the doubled slash makes the browser treat the target as a protocol-relative/cross-origin URL, sohistory.replaceStatethrowsDOMException. A cheap fix would be to normalize consecutive slashes (or at least strip a leading//after the origin) before anyreplaceState/pushStatecall in the navigation layer. Even without full normalization, guarding the history call so a malformed URL degrades to a plain navigation instead of crashing would prevent the hard failure. Happy to trace where the URL gets handed to history if a pointer helps.