Error in admin interface after 2.6.0 update

[sternchen]

Hello,

after upgrading to version 2.6.0 I'm getting

Your browser did not sent a valid HTTP-Referrer string. This may have either been caused by a misconfigured browser/proxy or by a Cross Site Request Forgery (XSRF) aimed at you. The action you requested could not be completed.

if I try to login into the admin interface.
After refreshing the page I can see the admin interface. All normal links are working, but as soon as I want to interact and press a dedicated button (like "Preview" or "Clear Cache" etc.) the same error message appears. So I can't really change anything. Commenting a blog post works, but not the admin interface.

The update itself was successful and the admin interface shows

Powered by Serendipity 2.6.0 and PHP 8.2.30

Any idea? Thank you very much!

[onli]

We changed how the XSRF protection works and now rely on a browser header - but the expectation was that the error won't happen then. Which browser do you use?