I fixed and recompiled the Native DLL for JSSC which was causing Access Violation crashes when attempting to open a serial port on Windows 10 64 bit systems with newer Java versions. With Java 8 x64, it was hit and miss. One system crashed while another did not. x32 always worked of course. With the recompiled DLL, everything works with all combinations. If however, you remove the USB serial device while it is open it will crash the JVM with the same Access Violation, but I never checked this behavior before as it may have been the same previously. Regardless, that is a small price to pay when everything works fine while its open. Attached is a fixed jssc.jar. Put this in your Libraries folder and re-compile your App, or you can insert the DLL directly into your app's jar. Either way. Also note that since the build is the same version number, you MUST go into your windows user profile folder and delete the cache .jssc folder. Java likes to use this instead of whats in the Jar!!!