Uninstalled and reinstalled JRE. No change.

Same Issue here on 2.40b8 :(

hi... same problem now

on board is version 2.40b8

it was not used long time

now i musst recalibrate gimbal but cant.

gui 2.40b8 crashes immidiatly when connect to board over com 4 and never version of gui cant read and upgrade FW.

before i use windows 7 ultimate. (PC) and windows 8.1 (Laptop)

now on both crashes.

#
# A fatal error has been detected by the Java Runtime Environment:
#
# EXCEPTION_ACCESS_VIOLATION (0xc0000005) at pc=0x000000006af484ee, pid=1788, tid=0x00000000000019b0
#
# JRE version: Java(TM) SE Runtime Environment (8.0_291-b10) (build 1.8.0_291-b10)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (25.291-b10 mixed mode windows-amd64 compressed oops)
# Problematic frame:
# C [libNRJavaSerial.dll+0x84ee]
#
# Failed to write core dump. Minidumps are not enabled by default on client versions of Windows
#
# If you would like to submit a bug report, please visit:
# http://bugreport.java.com/bugreport/crash.jsp
# The crash happened outside the Java Virtual Machine in native code.
# See problematic frame for where to report the bug.
#

--------------- T H R E A D ---------------

Current thread (0x000001e7a6f90000): JavaThread "ConnectThread" [_thread_in_native, id=6576, stack(0x0000009d41300000,0x0000009d41400000)]

siginfo: ExceptionCode=0xc0000005, reading address 0x00000000412fecdc

Registers:
RAX=0x000000000000001c, RBX=0x0000000000000003, RCX=0x0000009d413fed5c, RDX=0x00000000412fecd0
RSP=0x0000009d413fed00, RBP=0x0000000000000001, RSI=0x000001e7a6f90200, RDI=0x0000000000000000
R8 =0x0000009d413fe9d0, R9 =0x0000000000000000, R10=0x0000000000000000, R11=0x0000000000000200
R12=0x0000009d413ff1a8, R13=0x0000000000000000, R14=0x00000000412fecd0, R15=0x000001e7a6f90000
RIP=0x000000006af484ee, EFLAGS=0x0000000000010202

Top of Stack: (sp=0x0000009d413fed00)
0x0000009d413fed00: 00000007c0002368 000000006af5566b
0x0000009d413fed10: 0000000000000000 0000000000000001
0x0000009d413fed20: 0000f1598593bf35 000001e7a6f90000
0x0000009d413fed30: 0000009d413fee30 000000005f926ccc
0x0000009d413fed40: 74726f5058545852 29286e696172643a
0x0000009d413fed50: 736e727574657220 000000000a30203a
0x0000009d413fed60: 000000005fd99f10 000000005f9fd835
0x0000009d413fed70: 0000000000000004 0000000000000004
0x0000009d413fed80: 0000f1598593b895 000001e7a6f90000
0x0000009d413fed90: 000001e7893fb5d0 000000005f8af205
0x0000009d413feda0: 000001e7af690ff8 0000009d413fee30
0x0000009d413fedb0: 0000000000000000 0000009d413fef00
0x0000009d413fedc0: 000000076e2a5940 000000005f85f9f3
0x0000009d413fedd0: 000001e7a45d1d60 0000000000010100
0x0000009d413fede0: 000000005fdabc48 000001e7a41b50f0
0x0000009d413fedf0: 0000000000000003 0000000800000002

Instructions: (pc=0x000000006af484ee)
0x000000006af484ce: e8 ff 50 70 48 8b 06 48 89 da 48 89 f1 ff 90 b8
0x000000006af484de: 00 00 00 45 84 ed 75 0f 49 63 d6 48 85 d2 74 07
0x000000006af484ee: 8b 42 0c 85 c0 75 1b 31 c0 48 81 c4 d0 03 00 00
0x000000006af484fe: 5b 5e 5f 5d 41 5c 41 5d 41 5e c3 0f 1f 80 00 00


Register to memory mapping:

RAX=0x000000000000001c is an unknown value
RBX=0x0000000000000003 is an unknown value
RCX=0x0000009d413fed5c is pointing into the stack for thread: 0x000001e7a6f90000
RDX=0x00000000412fecd0 is an unknown value
RSP=0x0000009d413fed00 is pointing into the stack for thread: 0x000001e7a6f90000
RBP=0x0000000000000001 is an unknown value
RSI=0x000001e7a6f90200 is an unknown value
RDI=0x0000000000000000 is an unknown value
R8 =0x0000009d413fe9d0 is pointing into the stack for thread: 0x000001e7a6f90000
R9 =0x0000000000000000 is an unknown value
R10=0x0000000000000000 is an unknown value
R11=0x0000000000000200 is an unknown value
R12=0x0000009d413ff1a8 is pointing into the stack for thread: 0x000001e7a6f90000
R13=0x0000000000000000 is an unknown value
R14=0x00000000412fecd0 is an unknown value
R15=0x000001e7a6f90000 is a thread


Stack: [0x0000009d41300000,0x0000009d41400000], sp=0x0000009d413fed00, free space=1019k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
C [libNRJavaSerial.dll+0x84ee]
C 0x000001e78b0f990e

Java frames: (J=compiled Java code, j=interpreted, Vv=VM code)
j gnu.io.RXTXPort.nativeDrain(Z)Z+0
j gnu.io.RXTXPort$SerialOutputStream.flush()V+92
j sbgc.service.SerialCommandProcessor.sendCommand(Lsbgc/service/SerialCommand;)V+59
j sbgc.service.ConnectThread.run()V+80
v ~StubRoutines::call_stub

--------------- P R O C E S S ---------------

Java Threads: ( => current thread )
=>0x000001e7a6f90000 JavaThread "ConnectThread" [_thread_in_native, id=6576, stack(0x0000009d41300000,0x0000009d41400000)]
0x000001e7a6f93800 JavaThread "SerialPort" [_thread_in_native, id=13140, stack(0x0000009d41200000,0x0000009d41300000)]
0x000001e7a6f91800 JavaThread "D3D Screen Updater" daemon [_thread_blocked, id=8196, stack(0x0000009d41c00000,0x0000009d41d00000)]
0x000001e7a5b57000 JavaThread "TimerQueue" daemon [_thread_blocked, id=6944, stack(0x0000009d41700000,0x0000009d41800000)]
0x000001e7a60b2800 JavaThread "DestroyJavaVM" [_thread_blocked, id=3688, stack(0x0000009d3ff00000,0x0000009d40000000)]
0x000001e7a60a7800 JavaThread "EDT" [_thread_blocked, id=4580, stack(0x0000009d41100000,0x0000009d41200000)]
0x000001e7a6068000 JavaThread "AWT-Windows" daemon [_thread_in_native, id=7200, stack(0x0000009d41000000,0x0000009d41100000)]
0x000001e7a6066800 JavaThread "AWT-Shutdown" [_thread_blocked, id=12740, stack(0x0000009d40f00000,0x0000009d41000000)]


VM Arguments:
jvm_args: -Djava.library.path=./lib
java_command: C:\Users\D\Desktop\alexmos\SimpleBGC_GUI_2_40\SimpleBGC_GUI.jar
java_class_path (initial): C:\Users\D\Desktop\alexmos\SimpleBGC_GUI_2_40\SimpleBGC_GUI.jar
Launcher Type: SUN_STANDARD

Environment Variables:
PATH=C:\Program Files (x86)\Common Files\Oracle\Java\javapath;C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\System32\Wbem;C:\WINDOWS\System32\WindowsPowerShell\v1.0\;C:\Program Files (x86)\Common Files\Adobe\AGL;C:\WINDOWS\System32\OpenSSH\;C:\Program Files (x86)\AMD\ATI.ACE\Core-Static;C:\Users\D\AppData\Local\Microsoft\WindowsApps;;C:\Program Files\Java\jre1.8.0_291\bin
USERNAME=Modellbau
OS=Windows_NT
PROCESSOR_IDENTIFIER=AMD64 Family 21 Model 1 Stepping 2, AuthenticAMD



--------------- S Y S T E M ---------------

OS: Windows 10.0 , 64 bit Build 19041 (10.0.19041.928)

CPU:total 4 (initial active 4) (4 cores per cpu, 1 threads per core) family 21 model 1 stepping 2, cmov, cx8, fxsr, mmx, sse, sse2, sse3, ssse3, sse4.1, sse4.2, popcnt, avx, aes, clmul, mmxext, 3dnowpref, lzcnt, sse4a, tsc, tscinvbit, tscinv

Memory: 4k page, physical 16732944k(11484104k free), swap 19223312k(12442772k free)

vm_info: Java HotSpot(TM) 64-Bit Server VM (25.291-b10) for windows-amd64 JRE (1.8.0_291-b10), built on Apr 9 2021 00:02:00 by "java_re" with MS VC++ 15.9 (VS2017)

time: Fri May 7 20:54:50 2021
timezone: Mitteleuropäische Sommerzeit
elapsed time: 13.714659 seconds (0d 0h 0m 13s)

I signed up just to comment on this thread. THANK YOU! I just bought a second board and was about to send it back, but having the older version of Java worked for me. I couldnt connect to the board, each time it would crash immediately after hitting the connect button. And thank you for providing the link to the older version as well.

There are a couple of errors in the bat file: it should not be "Program Files (x86)" but just "Program Files", besides, the path should have jre1.8.0_231 (not jre1.8.0_321), so the final line of the bat file will be

@SET JAVA_EXE="C:\Program Files\Java\jre1.8.0_231\bin\javaw.exe"

%JAVA_EXE% -Dsimplebgc_gui.SimpleBGC_GUIView.Logger.level=0 -Djava.library.path="lib" -Dlog4j.configuration=log4j.properties -Dgnu.io.rxtx.NoVersionOutput=true -Dsun.java2d.dpiaware=false -jar "C:\Apps\SimpleBGC_GUI_2_43b9\SimpleBGC_GUI.jar"

"C:\Apps\SimpleBGC_GUI_2_43b9\SimpleBGC_GUI.jar" — is the path where the jar file is located in my case - replace it with your own.