Problems with monitor specification not found

OS (e.g. Win10):
PsychoPy version (2023.2.3):


I just updated my PsychoPy Version to 2023.2.3. and ran a simple experiment. The problem is that when I start the experiment (I tried it several times incl. restart) I get the info:
“Attempting to measure framerate of screen”
and as message I get:
“WARNING Monitor specification not found. Creating a temporary one…
ioHub Server Process Completed With Code: 0”

With the previous experiments everything worked fine. How can I solve this problem?
Thank you very much!