Hi,

again I don't see any major problem in libssh related output. But I see these:

qt.qpa.xcb: X server does not support XInput 2
qt.qpa.xcb: QXcbConnection: XCB error: 1 (BadRequest), sequence: 168,
resource id: 309, major code: 130 (Unknown), minor code: 47

NX does not support XInput 2. So these errors indicate the session has
been opened successfully but some application had a communication
problem with the X server (x2goagent in this case).

So chances are that xterm, libxcb, libX11 or any accompanying library
have been updated recently and are incompatible now. Maybe we can hunt
this down by checking this:
1. ssh -X <server> and run "nxagent -D -ac :55" there (nxagent window
should open up)
2. ssh server and run "DISPLAY=:55 xterm" there (xterm should open in
the nxagent window)

Does the xterm come up?

Also please repeat with "nxagent -R -ac :55". (no nxagent window will
come up, the xterm should open up in its own window in step 2)

Uli