Error occurs when using max_matches

If you have debugger onboard and installed debug symbols package for release, you can provide backtrace to us.
That is most probably from searchdsql.cpp line 532. If you set breakpoint there (after attaching to running instance with gdb), and then reproduce the error (so that breakpoint will be hit), you can issue command ‘where’ and attach the output (of course, you can check if that output doesn’t contains your sensitive data).