Panel crashes when witching to May 2017

Additionally an added backtrace of the Error:

#0 0x00007ffff5df2428 in __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:54
#1 0x00007ffff5df402a in __GI_abort () at abort.c:89
#2 0x00007ffff6403d65 in g_assertion_message () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3 0x00007ffff6403dfa in g_assertion_message_expr () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#4 0x00007fffd955c7e0 in util_date_range_construct () from /usr/lib/x86_64-linux-gnu/wingpanel/libdatetime.so
#5 0x00007fffd9560173 in util_event_date_ranges () from /usr/lib/x86_64-linux-gnu/wingpanel/libdatetime.so
#6 0x00007fffd9558c39 in date_time_widgets_calendar_model_get_events () from /usr/lib/x86_64-linux-gnu/wingpanel/libdatetime.so
#7 0x00007fffd95557c1 in ?? () from /usr/lib/x86_64-linux-gnu/wingpanel/libdatetime.so
#8 0x00007ffff63de04a in g_main_context_dispatch () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#9 0x00007ffff63de3f0 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#10 0x00007ffff63de49c in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#11 0x00007ffff7875d6d in g_application_run () from /usr/lib/x86_64-linux-gnu/libgio-2.0.so.0
#12 0x00007ffff7b70f30 in granite_application_run (self=0x7ec140, args=0x7fffffffdce8, args_length1=1)
    at /build/granite-EzORYV/granite-0.4.0.1+r980+pkg85~ubuntu0.4.1/obj-x86_64-linux-gnu/lib/Application.c:304
#13 0x0000000000407014 in wingpanel_main ()
#14 0x00007ffff5ddd830 in __libc_start_main (main=0x4065e0 <main>, argc=1, argv=0x7fffffffdce8, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>,
    stack_end=0x7fffffffdcd8) at ../csu/libc-start.c:291
#15 0x0000000000406619 in _start ()