Why is middle mouse button paste disabled in Ubuntu 26.04 and Fedora 44?

Problem:

Middle-Click Paste (is called Primary Paste) broke after upgrading to Ubuntu 26.04 and Fedora 44. GNOME 50 the Desktop Environment, used by Ubuntu and Fedora, disabled the button.

Jonathan Mainguy described this problem well in his blog.

Solution:

Re-enable primary paste for your user.

Step by step:

1. Open a Terminal, re-enable primary paste, execute:

   gsettings set org.gnome.desktop.interface gtk-enable-primary-paste true
   

2. Verify:

   gsettings get org.gnome.desktop.interface gtk-enable-primary-paste
   

Sources:

https://jmainguy.com/logbook/middle-click-paste-fedora-44/
https://www.freedesktop.org/wiki/Specifications/ClipboardsWiki/