FSUIPC 7.4.5 don not connect on MSFS and MSFS2024

[IN7504]

Good morning,

I installed FSUIPC version 7.5.4 for MSFS and MSFS2024 to use Java Simulator peripherals.

FSUIPC doesn't connect to the simulator, and if I launch the simulators via the FSUIPC application, they close.

Until last week, everything was working fine.

I attach the details of the error screen:

FSUIPC.FSUIPCException: FSUIPC Error #9: FSUIPC_ERR_NOTOPEN. The connection to FSUIPC is not open.

   in FSUIPC.FSUIPCConnection.ReadLVar(Byte ClassInstance, String LVAR)

   in JS_Connect_V4.MIP_FENIX.timer_CHK_Tick(Object sender, EventArgs e)

   in System.Windows.Forms.Timer.OnTick(EventArgs e)

   in System.Windows.Forms.Timer.TimerNativeWindow.WndProc(Message& m)

   in System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

 

 

 

************** Assembly caricati **************

 

mscorlib

 

    Versione assembly: 4.0.0.0

 

    Versione Win32: 4.8.9310.0 built by: NET481REL1LAST_C

 

    Base di codice: file:///C:/Windows/Microsoft.NET/Framework64/v4.0.30319/mscorlib.dll

 

----------------------------------------

 

JS-Connect_V4

 

    Versione assembly: 1.0.0.0

 

    Versione Win32: 1.0.0.0

 

    Base di codice: file:///C:/FSUIPC7/JS-Connect/JS-Connect_V4.exe

 

----------------------------------------

 

System.Windows.Forms

 

    Versione assembly: 4.0.0.0

 

    Versione Win32: 4.8.9256.0 built by: NET481REL1LAST_B

 

    Base di codice: file:///C:/WINDOWS/Microsoft.Net/assembly/GAC_MSIL/System.Windows.Forms/v4.0_4.0.0.0__b77a5c561934e089/System.Windows.Forms.dll

 

----------------------------------------

 

System

 

    Versione assembly: 4.0.0.0

 

    Versione Win32: 4.8.9320.0 built by: NET481REL1LAST_B

 

    Base di codice: file:///C:/WINDOWS/Microsoft.Net/assembly/GAC_MSIL/System/v4.0_4.0.0.0__b77a5c561934e089/System.dll

 

----------------------------------------

 

System.Drawing

 

    Versione assembly: 4.0.0.0

 

    Versione Win32: 4.8.9032.0 built by: NET481REL1

 

    Base di codice: file:///C:/WINDOWS/Microsoft.Net/assembly/GAC_MSIL/System.Drawing/v4.0_4.0.0.0__b03f5f7f11d50a3a/System.Drawing.dll

 

----------------------------------------

 

fsuipcClient

 

    Versione assembly: 3.3.12.414

 

    Versione Win32: 3.3.12.414

 

    Base di codice: file:///C:/FSUIPC7/JS-Connect/fsuipcClient.DLL

 

----------------------------------------

 

System.Configuration

 

    Versione assembly: 4.0.0.0

 

    Versione Win32: 4.8.9032.0 built by: NET481REL1

 

    Base di codice: file:///C:/WINDOWS/Microsoft.Net/assembly/GAC_MSIL/System.Configuration/v4.0_4.0.0.0__b03f5f7f11d50a3a/System.Configuration.dll

 

----------------------------------------

 

System.Core

 

    Versione assembly: 4.0.0.0

 

    Versione Win32: 4.8.9316.0 built by: NET481REL1LAST_C

 

    Base di codice: file:///C:/WINDOWS/Microsoft.Net/assembly/GAC_MSIL/System.Core/v4.0_4.0.0.0__b77a5c561934e089/System.Core.dll

 

----------------------------------------

 

System.Xml

 

    Versione assembly: 4.0.0.0

 

    Versione Win32: 4.8.9032.0 built by: NET481REL1

 

    Base di codice: file:///C:/WINDOWS/Microsoft.Net/assembly/GAC_MSIL/System.Xml/v4.0_4.0.0.0__b77a5c561934e089/System.Xml.dll

 

----------------------------------------

 

Accessibility

 

    Versione assembly: 4.0.0.0

 

 

 

Do you have any advice for me?

Thank you very much.

 

[John Dowson]

18 minutes ago, IN7504 said:

if I launch the simulators via the FSUIPC application, they close.

What do you mean by this? FSUIPC does not launch MSFS. The desktop icon installed with FSUIPC only starts MSFS, and then MSFS will start FSUIPC via the EXE.xml (if/when using the auto-start feature).

18 minutes ago, IN7504 said:

FSUIPC doesn't connect to the simulator

Does this occur with both MSFS2020 and MSFS2024? If FSUIPC is not connecting, I need to see your FSUIPC7.log file - please show me / attach this.
If there are connection issues, see the following FAQ entry: 

 

18 minutes ago, IN7504 said:

Until last week, everything was working fine.

What has changed since then?

John

P.S. Do you mean 7.5.4 (not 7.4.5)? If so, were you previously using 7.5.3? If so, I can provide you with that version to check its not an issue with the new version.

Edited Monday at 06:34 PM by John Dowson
PS added

[IN7504]

Good evening, Mr. Dowson, thank you for your timely  response.

Yes, until two days ago I was using version 7.5.3.

I'm having this problem with both MSFS2020 and MSFS2024.

When I launch one of the two simulators using the icon generated by installing FSUIPC, a screen appears saying "FSUIPC is preparing the cabin. Please what..." and then closes shortly thereafter.

Andrea

 

FSUIPC7.ini

[John Dowson]

12 hours ago, IN7504 said:

When I launch one of the two simulators using the icon generated by installing FSUIPC, a screen appears saying "FSUIPC is preparing the cabin. Please what..." and then closes shortly thereafter.

Yes - those icons start MSFS and display the 'preparing the cabin' splash screen while MSFS starts-up.
Does MSFS actually then start?
Once it starts, MSFS should then start FSUIPC - you will see the FSUIPC splash screen when this is starting (unless you have disabled this).

If MSFS is not auto-starting FSUIPC7, then see this FAQ entry: 

You can also start FSUIPC7 manually (by double-clicking the FSUIPC7.exe) to see if the issue is just that FSUIPC7 is not running.

If it is running but cannot connect, I need to see you FSUIPC7.log file (not the FSUIPC7.ini file which you attached).

If there were issues installing the auto-start component (i.e. updating your EXE.xml files), then there should also be an error in your InstallFSUIPC7.log file, so take a look at that. You can also show me / attach this file.

John

 

[IN7504]

6 hours ago, John Dowson said:

Yes - those icons start MSFS and display the 'preparing the cabin' splash screen while MSFS starts-up.
Does MSFS actually then start?
Once it starts, MSFS should then start FSUIPC - you will see the FSUIPC splash screen when this is starting (unless you have disabled this).

No, MSFS won't start, the screen closes, and nothing happens.

If I start it using the traditional icon, the simulator loads correctly, but without FSUIPC.

 

[John Dowson]

3 minutes ago, IN7504 said:

No, MSFS won't start, the screen closes, and nothing happens.

Ok - then we need to determine why MSFS isn't being started. Can you show me / attach your InstallFSUIPC7.log file please. Are you using a steam or a MS Store installation for MSFS2020/MSFS2024?

5 minutes ago, IN7504 said:

If I start it using the traditional icon, the simulator loads correctly, but without FSUIPC.

If MSFS is not auto-starting FSUIPC7, then you need to see that link I previously posted. Your installation log may also tell you what the issue is here.

Your application cannot connect if FSUIPC is not running. Have you tried starting it manually?

 

[IN7504]

6 hours ago, John Dowson said:

You can also start FSUIPC7 manually (by double-clicking the FSUIPC7.exe) to see if the issue is just that FSUIPC7 is not running.

If it is running but cannot connect, I need to see you FSUIPC7.log file (not the FSUIPC7.ini file which you attached).

If there were issues installing the auto-start component (i.e. updating your EXE.xml files), then there should also be an error in your InstallFSUIPC7.log file, so take a look at that. You can also show me / attach this file.

John, I'm attaching the requested file.

I launched FSUIPC via .exe and it starts correctly, but it doesn't connect with Java Simulator's JSconnect.

 

FSUIPC7.log

[John Dowson]

19 minutes ago, IN7504 said:

I'm attaching the requested file.

As I keep saying, I need to see your InstallFSUIPC7.log file - please attach that....

19 minutes ago, IN7504 said:

I launched FSUIPC via .exe and it starts correctly, but it doesn't connect with Java Simulator's JSconnect.

Your log shows a few connection attempts before a connection to MSFS was established. This was because you manually started FSUIPC7 to early - when manually starting, you should wait until MSFS has arrived at the main menu.

Other than that, the log looks ok. Did you start your java program before or after FSUIPC was connected to MSFS? Try starting it once FSUIPC7 is connected to see of that helps, or after you have an aircraft loaded and ready-to-fly.

I have also attached the previous version for you to try, 7.5.3. Temporarily rename your current FSUIPC7.exe and use this to see if there is a difference.

FSUIPC7.exe

[IN7504]

Ok I started FSUIPC after the simulator started and then I started JS Connect and the error appeared: FSUIPC Error #9: FSUIPC_ERR_NOTOPEN. The connection to FSUIPC is not open.

I'm attaching InstallFSUIPC7

 

Now I'll try version 7.5.3

 

InstallFSUIPC7.log

[John Dowson]

Your install log looks fine - no errors or issues.

There is one thing that could be causing these issues - you are running FSUIPC7 with elevated privileges from the log file you attached earlier:

Quote

********* FSUIPC7, Version 7.5.4 (13th July 2025) by John Dowson *********
WebSocket server found: C:\FSUIPC7\\Utils\FSUIPCWebSocketServer.exe
Windows 11 detected - setting DisableMSFSMonitor to 'Enum'
Windows 10 Pro 64 Bit reported as Build 26100, Release ID: 2009 (OS 10.0)
FSUIPC is running with elevated privileges
Reading options from "C:\FSUIPC7\FSUIPC7.ini"
...

Why are you running with elevated privileges? If you run FSUIPC7 with elevated privileges, then you must also run your java program (and all FSUIPC client programs) at the same privilege level, otherwise it won't connect. Are you dong this?

And are you also running MSFS with elevated privileges, and if so, why?

If MSFS is not running with elevated privileges, then it won't be able to auto-start FSUIPC7 if that is set to run with elevated privileges.

If you have set the FSUIPC7.exe to be ran with elevated privileges, remove this.

If you ran the FSUIPC7 installer as admin (i.e. with elevated privileges), then uninstall, and then re-install as a standard user. The installer will request the privileges it needs which you need to approve, but it should not be ran as admin.

John

 

[IN7504]

Yessssss

Thanks a lot John, I changed the privileges of both Fsuipc and Js connect and now it works!!!

🤩