Thanks for your report.
I have sent you an email with a debug version of WinSCP to the address you have used to register on this forum.

Good Morning,

I'm having trouble authenticating according to the error below.

open scp://user@server:2222/ -privatekey=PrivateKey.ppk

-----------------------
Authenticating...
Using username "....".
Authenticating with public key "rsa-key-...".
Invalid access to memory.
Please help us improving WinSCP by reporting the error on WinSCP support forum.
Stack trace:
(00BCC150) _conf_get_bool
(00F85292) C5296_3
(00F872FA) ____ExceptionHandler
(00F840B4) __ExceptionHandler
(0003141E) ntdll.dll.RtlRaiseStatus
(0002F1C6) ntdll.dll.KiUserExceptionDispatcher
(00BD4000) _mainchan_new
(00BEB9F1) _ssh2_serverside_agent_open
(00BEA09A) _ssh2_connection_new
(00BEA318) _ssh2_connection_new
(00BFD149) _ssh_ppl_free
(00BCBC36) C2603_0
(00BCBD29) _run_toplevel_callbacks
(00D05668) TSecureShell::EventSelectLoop
(00D0454B) TSecureShell::WaitForData
(00CFF509) TSecureShell::Init
(00CFEE49) TSecureShell::Open
(00D86F65) TTerminal::Open
(00CF1F5E) TScript::ConnectTerminal
(00CFB71A) TManagementScript::OpenProc
(00CEF339) TScriptCommands::Execute
(00CF08CB) TScript::Command
(00060F93) TConsoleRunner::Run
(00068993) Console
(001005AD) Execute
(00002658) wWinMain
(00F832A5) __wstartup
(00048E77) ntdll.dll
(00048E47) ntdll.dll
Authentication log (see session log for details):
Using username "....".
Authenticating with public key "rsa-key-...".
-----------------------