While Thunar was in background, it crashed by hitting with the following assertion:

#0  0x003f5416 in __kernel_vsyscall ()
#1  0x426b698f in __GI_raise (sig=6) at ../nptl/sysdeps/unix/sysv/linux/raise.c:64
#2  0x426b82d5 in __GI_abort () at abort.c:91
#3  0x426f702a in __libc_message (do_abort=2, fmt=0x427f194c "*** glibc detected *** %s: %s: 0x%s ***\n") at ../sysdeps/unix/sysv/linux/libc_fatal.c:198
#4  0x426fdf12 in malloc_printerr (action=<optimized out>, str=<optimized out>, ptr=0xaf54f230) at malloc.c:5021
#5  0x426ff1e3 in _int_free (av=0xaf500010, p=0xaf54f1c8, have_lock=0) at malloc.c:4097
#6  0x42792cc1 in __GI___vasprintf_chk (result_ptr=0xaf4fef3c, flags=1, format=0x80cdd3c "%s.png", args=0xaf4fef74 "؛Z\257\377\377\377\377")
    at vasprintf_chk.c:86
#7  0x429769a7 in vasprintf (__ap=0xaf4fef74 "؛Z\257\377\377\377\377", __fmt=0x80cdd3c "%s.png", __ptr=0xaf4fef3c) at /usr/include/bits/stdio2.h:199
#8  g_vasprintf (string=0xaf4fef3c, format=0x80cdd3c "%s.png", args=0xaf4fef74 "؛Z\257\377\377\377\377") at gprintf.c:314
#9  0x4294f664 in g_strdup_vprintf (format=0x80cdd3c "%s.png", args=0xaf4fef74 "؛Z\257\377\377\377\377") at gstrfuncs.c:253
#10 0x4294f694 in g_strdup_printf (format=0x80cdd3c "%s.png") at gstrfuncs.c:279
#11 0x0807635e in thunar_file_load (file=0xacbad630, cancellable=0x0, error=0xaf4ff01c) at thunar-file.c:894
#12 0x080780c6 in thunar_file_get (gfile=0x9175380, error=0xaf4ff01c) at thunar-file.c:631
#13 0x0807defe in _thunar_io_jobs_ls (job=0x930fd20, param_values=0xaf5276a0, error=0xaf4ff06c) at thunar-io-jobs.c:1179
#14 0x080a8a89 in thunar_simple_job_execute (job=0x930fd20, error=0xaf4ff0ac) at thunar-simple-job.c:115
#15 0x43d76b8c in exo_job_scheduler_job_func (scheduler_job=0x9299e08, cancellable=0x9228180, user_data=0xaf70ef20) at exo-job.c:331
#16 0x42c6485c in io_job_thread (data=0x9299e08, user_data=0x0) at gioscheduler.c:180
#17 0x4295a3bf in g_thread_pool_thread_proxy (data=0x92598b8) at gthreadpool.c:319
#18 0x42957f45 in g_thread_create_proxy (data=0x92c91f8) at gthread.c:1962
#19 0x42844cd3 in start_thread (arg=0xaf4ffb40) at pthread_create.c:309
#20 0x4277aa2e in clone () at ../sysdeps/unix/sysv/linux/i386/clone.S:133