magit error

[Dieter Faulbaum]

Hello,

if I call 'M-x magit' I get (today) this error:
load-with-code-conversion: Symbol’s function definition is void: 
transient-define-group

Under 'M-x list-packages' I see, I have two transient packages:
 transient                      20250520.1040 dependency 
 Transient commands.
 transient                      0.8.6         built-in 
 Transient commands

Is there something wrong (with the two packages)?
And what can I do?

I removed the first package and compiled the emacs (up-to-date one 
from git) new, but these both trials don't help.-(

Any better idea?