Tried with 3.48.22 and 3.48.21 on Gentoo Linux, terminating like so:

Caught signal 11
httrack[0x402273]
/lib64/libc.so.6(+0x33080)[0x7f2d0ee80080]
/lib64/libc.so.6(+0x7e363)[0x7f2d0eecb363]
/usr/lib64/libhttrack.so.2(+0x4e3b9)[0x7f2d0f2333b9]
/usr/lib64/libhttrack.so.2(hts_main2+0x42)[0x7f2d0f239d62]
httrack[0x401a6c]
/lib64/libc.so.6(__libc_start_main+0xf5)[0x7f2d0ee6d6a5]
httrack[0x401b39]