samba - Dec 2018 - [Samba 4.9.2] Panic error, BACKTRACE: 45 on Ubuntu 16.04

Dear all,
I've an issue with my samba installation with a version of samba 4.9.2 that
I’ve compiled for Ubuntu 16.04.
Samba works without any particular issues until I try to use the sharing for
Time Machine backup. In fact,
after starting the Time Machine backup after a while, random time like 2-3 hours
of backup, I got the following
panic error and the backup stops and I need to reboot samba.

[2018/12/09 11:43:57.461725,  0]
../source3/locking/share_mode_lock.c:439(share_mode_data_destructor)
 store returned NT_STATUS_UNSUCCESSFUL
[2018/12/09 11:43:57.461915,  0] ../source3/lib/util.c:816(smb_panic_s3)
 PANIC (pid 32610): could not store share mode entry: NT_STATUS_UNSUCCESSFUL
[2018/12/09 11:43:57.463585,  0] ../lib/util/fault.c:261(log_stack_trace)
 BACKTRACE: 45 stack frames:
  #0 /usr/lib/x86_64-linux-gnu/libsamba-util.so.0(log_stack_trace+0x2e)
[0x7fa1ab8af95f]
  #1 /usr/lib/x86_64-linux-gnu/libsmbconf.so.0(smb_panic_s3+0x6d)
[0x7fa1ab01709a]
  #2 /usr/lib/x86_64-linux-gnu/libsamba-util.so.0(smb_panic+0x28)
[0x7fa1ab8af91b]
  #3 /usr/lib/x86_64-linux-gnu/samba/libsmbd-base-samba4.so(+0x28a9ad)
[0x7fa1ab4fb9ad]
  #4 /usr/lib/x86_64-linux-gnu/samba/libtalloc.so.2(+0x3697) [0x7fa1aa9c4697]
  #5 /usr/lib/x86_64-linux-gnu/samba/libtalloc.so.2(+0x492c) [0x7fa1aa9c592c]
  #6 /usr/lib/x86_64-linux-gnu/samba/libtalloc.so.2(+0x3852) [0x7fa1aa9c4852]
  #7 /usr/lib/x86_64-linux-gnu/samba/libtalloc.so.2(+0x492c) [0x7fa1aa9c592c]
  #8 /usr/lib/x86_64-linux-gnu/samba/libtalloc.so.2(+0x3852) [0x7fa1aa9c4852]
  #9 /usr/lib/x86_64-linux-gnu/samba/libtalloc.so.2(+0x3a13) [0x7fa1aa9c4a13]
  #10 /usr/lib/x86_64-linux-gnu/samba/libtalloc.so.2(_talloc_free+0x105)
[0x7fa1aa9c5d79]
  #11 /usr/lib/x86_64-linux-gnu/samba/libsmbd-base-samba4.so(+0x1dfefd)
[0x7fa1ab450efd]
  #12 /usr/lib/x86_64-linux-gnu/samba/libsmbd-base-samba4.so(+0x1e36dc)
[0x7fa1ab4546dc]
  #13
/usr/lib/x86_64-linux-gnu/samba/libsmbd-base-samba4.so(create_file_default+0x330)
[0x7fa1ab45532f]
  #14 /usr/lib/x86_64-linux-gnu/samba/libsmbd-base-samba4.so(+0x105027)
[0x7fa1ab376027]
  #15
/usr/lib/x86_64-linux-gnu/samba/libsmbd-base-samba4.so(smb_vfs_call_create_file+0xa9)
[0x7fa1ab46131c]
  #16 /usr/lib/x86_64-linux-gnu/samba/vfs/fruit.so(+0x170d3) [0x7fa1932910d3]
  #17
/usr/lib/x86_64-linux-gnu/samba/libsmbd-base-samba4.so(smb_vfs_call_create_file+0xa9)
[0x7fa1ab46131c]
  #18 /usr/lib/x86_64-linux-gnu/samba/libsmbd-base-samba4.so(+0x23625a)
[0x7fa1ab4a725a]
  #19
/usr/lib/x86_64-linux-gnu/samba/libsmbd-base-samba4.so(smbd_smb2_request_process_create+0x7ab)
[0x7fa1ab4a4d2b]
  #20
/usr/lib/x86_64-linux-gnu/samba/libsmbd-base-samba4.so(smbd_smb2_request_dispatch+0x13bb)
[0x7fa1ab498367]
  #21 /usr/lib/x86_64-linux-gnu/samba/libsmbd-base-samba4.so(+0x22b51d)
[0x7fa1ab49c51d]
  #22 /usr/lib/x86_64-linux-gnu/samba/libsmbd-base-samba4.so(+0x22b637)
[0x7fa1ab49c637]
  #23
/usr/lib/x86_64-linux-gnu/samba/libtevent.so.0(tevent_common_invoke_fd_handler+0x101)
[0x7fa1aa5adb66]
  #24 /usr/lib/x86_64-linux-gnu/samba/libtevent.so.0(+0x11422) [0x7fa1aa5b8422]
  #25 /usr/lib/x86_64-linux-gnu/samba/libtevent.so.0(+0x11af6) [0x7fa1aa5b8af6]
  #26 /usr/lib/x86_64-linux-gnu/samba/libtevent.so.0(+0xe30b) [0x7fa1aa5b530b]
  #27 /usr/lib/x86_64-linux-gnu/samba/libtevent.so.0(_tevent_loop_once+0x11e)
[0x7fa1aa5acd95]
  #28
/usr/lib/x86_64-linux-gnu/samba/libtevent.so.0(tevent_common_loop_wait+0x25)
[0x7fa1aa5ad0e3]
  #29 /usr/lib/x86_64-linux-gnu/samba/libtevent.so.0(+0xe3ad) [0x7fa1aa5b53ad]
  #30 /usr/lib/x86_64-linux-gnu/samba/libtevent.so.0(_tevent_loop_wait+0x2b)
[0x7fa1aa5ad186]
  #31 /usr/lib/x86_64-linux-gnu/samba/libsmbd-base-samba4.so(smbd_process+0xbdf)
[0x7fa1ab47f493]
  #32 /usr/sbin/smbd(+0xdaf9) [0x55e43ec29af9]
  #33
/usr/lib/x86_64-linux-gnu/samba/libtevent.so.0(tevent_common_invoke_fd_handler+0x101)
[0x7fa1aa5adb66]
  #34 /usr/lib/x86_64-linux-gnu/samba/libtevent.so.0(+0x11422) [0x7fa1aa5b8422]
  #35 /usr/lib/x86_64-linux-gnu/samba/libtevent.so.0(+0x11af6) [0x7fa1aa5b8af6]
  #36 /usr/lib/x86_64-linux-gnu/samba/libtevent.so.0(+0xe30b) [0x7fa1aa5b530b]
  #37 /usr/lib/x86_64-linux-gnu/samba/libtevent.so.0(_tevent_loop_once+0x11e)
[0x7fa1aa5acd95]
  #38
/usr/lib/x86_64-linux-gnu/samba/libtevent.so.0(tevent_common_loop_wait+0x25)
[0x7fa1aa5ad0e3]
  #39 /usr/lib/x86_64-linux-gnu/samba/libtevent.so.0(+0xe3ad) [0x7fa1aa5b53ad]
  #40 /usr/lib/x86_64-linux-gnu/samba/libtevent.so.0(_tevent_loop_wait+0x2b)
[0x7fa1aa5ad186]
  #41 /usr/sbin/smbd(+0xe809) [0x55e43ec2a809]
  #42 /usr/sbin/smbd(main+0x190e) [0x55e43ec2caf7]
  #43 /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xf0) [0x7fa1a7845830]
  #44 /usr/sbin/smbd(_start+0x29) [0x55e43ec22089]

This is my smb.conf configuration

[global]
	load printers = no
	printcap name = /dev/null
	obey pam restrictions = yes
	max log size = 1000
	use mmap = no
	dns proxy = no
	map to guest = bad user
	log file = /var/log/samba/%m.log
	fruit:model = MacPro
	netbios name = sambaudoo
	server role = standalone server
	acl allow execute always = yes
	follow symlinks = yes
	interfaces = wlp3s0
	fruit:advertise_fullsync = true
	server string = Samba Server %v
	wide links = yes
	unix extensions = no
	socket options = SO_KEEPALIVE
	keepalive = 90
	security = user

#Share
[TimeMachine Home]
path = mypath
valid users = %U
writable = yes
durable handles = yes
kernel oplocks = no
kernel share modes = no
posix locking = no
vfs objects = catia fruit streams_xattr
ea support = yes
browseable = yes
read only = No
inherit acls = yes
fruit:time machine = yes
hide dot files = yes

How can I fix this panic error?

Thanks a lot

—
Piero