2.4.2.1 exits on Mac Sequoia 15.0.1 Intel but not Silicon

[Eberhard W Lisse]

Hi,

I upgraded my intel mac laptop to 15.0.1 (quitting LyX before restarting
the machine) and when I open LyX or a LyX document now it opens and
closes immediately.

When I do that on the command line it shows the following

   qt.qpa.fonts: Populating font family aliases took 399 ms. Replace
uses of missing font family "Serif" with one that exists to avoid this cost.

The fonts warning I have on the Silicon machine too and for a while now.

   Server.cpp (1016): LyX is already running in another instance
   and 'use single instance' is active.


However, LyX is NOT running (pax aux|grep -i lyx) shows nothing.

If I do this on the Silicon with LyX running I get the same error and if
it is not, I don't and LyX starts as intended.

Any idea where I can look? And how?

Can I turn 'single instance' off somewhere/somehow?

greetings, el