Round Cube email now not allowing Dark Reader to enable. This is of May 25, 2026.

It might be good to let Dark Reader folks know: https://github.com/darkreader/darkreader/issues in case there's some incompatibility with Roundcube sites in an upcoming release.

At the same time you can try to go to an older version Nightly to attempt confirming it's not just a site/add-on issue, and works in a Nightly build A, but breaks starting from build B.

Interestingly, I have the Dark Reader installed on Microsoft Edge and Round Cube works fine. I can enable it on Round Cube, disable it and enable it again. The issue seems to be with Firefox Nightly itself. What I have not done, is install basic Firefox and see how that works. As the gentleman once said, "I'll be back".

Dark Reader has different implementation paths for browser engines.

If the broken thing is the actual "toggle" on darkreader's own pane, then definitely please report to the add-on authors.

It sure might be a Nightly change they're not ready for, might be a good heads up, or might go away in a version or two on its own — but unless you can report the platform bug I'd defer to the add-on maintainers to figure out why it's broken, and if they need to file a bug for something that's getting in their way.

I'll send a note to the Author of Dark Reader. As far as de-bugging Nightly, I am not much of a coder. If someone were to point to where I would begin to problem solve, I may be able to isolate something there. If you folks are experienced at debugging/coding Firefox, then consider I am still learning to tie my shoes here.

On a thought, I opened the Dark Reader settings / site list of "Disabled" sites, and manually removed the site hosting my Round Cube Email.

Happy to report, Dark Reader is now enabled for Round Cube.

To those responding to my post, thank you for taking the time to post a thought.

Cheers