Sounds like a bug. If you can reproduce it, hit the “innermost” Syncthing process with a SIGQUIT to produce a full stack trace that we can use to diagnose it. That process has the higher PID of two. That is:
$ ps aux | grep syncthing
# get either one PID, or two. If two, take the highest
$ kill -QUIT $pidOfSyncthing
Then post the backtrace somewhere ![]()