Comment # 11 on bug 1222583 from Larry Rainey

I found the cure

you have to have dconf-editor installed an reboot and the panels will not
abort.

I compared the latest fedora 40 beta with the 20 day old one that did not work
and installed dconf-editor and fedora 40 worked

Did the same to my Tumbleweed and panels now work.

As root:

LLR3:~ # zypper in dconf-editor
Loading repository data...
Reading installed packages...
Resolving package dependencies...

The following NEW package is going to be installed:
  dconf-editor

1 new package to install.
Overall download size: 301.3 KiB. Already cached: 0 B. After the operation,
additional 987.6 KiB will be used.

Backend:  classic_rpmtrans
Continue? [y/n/v/...? shows all options] (y): 
Retrieving: dconf-editor-45.0.1-2.3.x86_64 (openSUSE-Tumbleweed-Oss)
                                                            (1/1), 301.3 KiB    
Retrieving: dconf-editor-45.0.1-2.3.x86_64.rpm ..............[done (80.0
KiB/s)]

Checking for file conflicts:
.............................................[done]
(1/1) Installing: dconf-editor-45.0.1-2.3.x86_64
.........................[done]
Running post-transaction scripts
.........................................[done]
LLR3:~ #