[Qgis-user] Loading older Qgis project stalls / unresponsive UI

[Christian Barthel]

Hi, I am trying to load some older Qgis projects (3.22.16, Debian
12) with a newer Qgis version (3.40.6 on Debian 13).  The message
"Project file is older" is shown at the top and for some
projects, Qgis just "hangs" and it seems to do nothing (strace
shows a futex() system call and nothing is changing anymore).
Qgis is totally unresponsive and I had to kill the app then.

Is there some way to debug this problem?
How can I find out why my projects are not loaded?

I know that there are layers for which the data source is no
longer available but usually there was a message where I can
ignore those.  The Project file is a readable xml,  though I
wonder if I should try to remove some of the layers manually?

Thanks! 

-- 
Christian Barthel