Additionally informed contextmenu plugin author about the issue https://github.com/JohnDoh/Roundcube-Plugin-Context-Menu/issues/73. The fix on contextmenu side is needed to make sure similiar errors aren't thrown in other places with the same code path.

Note there's also Save as Task dialog which if contained Attachments tab would also collide. The best solution should fix both and allow extending the Save as Task dialog with Attachment tab later.

Implemented for Files, not for Mail.

It is already highlighted by

.calendarmain .fc-state-highlight {
    background-color: rgba(244, 196, 37, 0.1);
}

https://git.kolab.org/M4

Adding architecture, as this obviously have impact on the world

I'd like to propose Rocket.Chat. Maybe its not quite there yet but neither is this issue seemingly :)

That's a different issue. Probably fixed by this https://git.kolab.org/rIbb534210020c5fedd9c4b780c995e8b7c20d81a6

The error remains.

Patched the internal webservers, @vincent is testing.

Done in 5802e08e4833.

The Sabre/VObject is in version 2.1.7, so it should be fine.

BTW: Still seeing these after the recent Kolab Now service window. Should it have resolved them or is this something new/residual?

Getting OTP would be wonderful. I do own a Yubikey Edge, which is configured for OATH-HOTP and Challenge-Response HMAC-SHA1 (and U2F). I do use Challenge-Response for offline things like keepass, LUKS or Laptop-Login.

Real fix in git. To hotfix production servers the patch from https://issues.kolab.org/show_bug.cgi?id=5190#c2 can be used.