i have in my configs the following lines:

10-mail.conf:mail_attribute_dict =
file:/srv/vmail/dovecot/metadata/%d/%n/attributes 20-imap.conf:imap_metadata = yes

when i test GETMETADATA with telnet i got a pannic in my error.log
file and no attributes file in the given location is created

root@i920:/etc/dovecot/conf.d# telnet localhost imap Trying 127.0.0.1... Connected to localhost. Escape character is '^]'.

• OK [CAPABILITY IMAP4rev1 LITERAL+ SASL-IR LOGIN-REFERRALS ID ENABLE
  IDLE STARTTLS AUTH=PLAIN AUTH=LOGIN] Dovecot ready. 01 LOGIN tester@domain.com ********* 01 OK [CAPABILITY IMAP4rev1 LITERAL+ SASL-IR LOGIN-REFERRALS ID ENABLE
  IDLE SORT SORT=DISPLAY THREAD=REFERENCES THREAD=REFS
  THREAD=ORDEREDSUBJECT MULTIAPPEND URL-PARTIA L CATENATE UNSELECT CHILDREN NAMESPACE UIDPLUS LIST-EXTENDED
  I18NLEVEL=1 CONDSTORE QRESYNC ESEARCH ESORT SEARCHRES WITHIN
  CONTEXT=SEARCH LIST-STATUS SPECIAL-USE BINARY MOVE SEARCH=FUZZY NOTIFY METADATA COMPRESS=DEFLATE QUOTA ACL
  RIGHTS=texk] Logged in 02 GETMETADATA "*" (/shared/test) Connection closed by foreign host.

in error.log i have these lines: Dec 23 17:20:00 imap(tester@domain.com): Panic: file imap-client.c:
line 634 (client_command_free): assertion failed:
(client->output_cmd_lock == NULL) Dec 23 17:20:00 imap(tester@domain.com): Error: Raw backtrace:
/usr/lib/dovecot/libdovecot.so.0(+0x5e900) [0x7fb053bea900] ->
/usr/lib/dovecot/libdovecot.so.0(+0x5e9de) [0x7fb053bea9de] ->
/usr/lib/dovecot/libdovecot.so.0(i_fatal+0) [0x7fb053ba5bfe] ->
dovecot/imap() [0x415c17] -> dovecot/imap() [0x415d8a] ->
dovecot/imap() [0x415e15] -> dovecot/imap(client_handle_input+0x115)
[0x416115] -> dovecot/imap(client_input+0x72) [0x4164a2] ->
/usr/lib/dovecot/libdovecot.so.0(io_loop_call_io+0x27)
[0x7fb053bfa8f7] ->
/usr/lib/dovecot/libdovecot.so.0(io_loop_handler_run+0xd7)
[0x7fb053bfb687] -> /usr/lib/dovecot/libdovecot.so.0(io_loop_run+0x38)
[0x7fb053bfa498] ->
/usr/lib/dovecot/libdovecot.so.0(master_service_run+0x13)
[0x7fb053baadf3] -> dovecot/imap(main+0x2af) [0x40b06f] ->
/lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xf5)
[0x7fb0537e5de5] -> dovecot/imap() [0x40b1cc]

gdb with bt full gives: #0 0x00007f174b6bdf77 in raise () from /lib/x86_64-linux-gnu/libc.so.6 No symbol table info available. #1 0x00007f174b6c15e8 in abort () from /lib/x86_64-linux-gnu/libc.so.6 No symbol table info available. #2 0x00007f174baad8f6 in default_fatal_finish (type=<optimized out>,
status=status@entry=0) at failures.c:193 backtrace = 0x1801040
"/usr/lib/dovecot/libdovecot.so.0(+0x5e900) [0x7f174baad900] ->
/usr/lib/dovecot/libdovecot.so.0(+0x5e9de) [0x7f174baad9de] ->
/usr/lib/dovecot/libdovecot.so.0(i_fatal+0) [0x7f174ba68bfe] ->
dovecot/im"... #3 0x00007f174baad9de in i_internal_fatal_handler
(ctx=0x7fffe2002eb0, format=<optimized out>, args=<optimized out>) at
failures.c:657 status = 0 #4 0x00007f174ba68bfe in i_panic (format=format@entry=0x423040 "file
%s: line %d (%s): assertion failed: (%s)") at failures.c:267 ctx = {type = LOG_TYPE_PANIC, exit_status = 0, timestamp = 0x0} args = {{gp_offset = 40, fp_offset = 48, overflow_arg_area =
0x7fffe2002fa0, reg_save_area = 0x7fffe2002ee0}} #5 0x0000000000415c17 in client_command_free
(_cmd=_cmd@entry=0x7fffe2002fc8) at imap-client.c:634 cmd = 0x183a2d0 client = 0x18396f0 state = CLIENT_COMMAND_STATE_WAIT_INPUT __FUNCTION__ = "client_command_free" #6 0x0000000000415d8a in client_command_input (cmd=0x0) at imap-client.c:783 client = 0x18396f0 command = <optimized out> __FUNCTION__ = "client_command_input" #7 0x0000000000415e15 in client_command_input (cmd=0x183a2d0) at
imap-client.c:841 client = 0x18396f0 command = <optimized out> __FUNCTION__ = "client_command_input" #8 0x0000000000416115 in client_handle_next_command
(remove_io_r=<synthetischer Zeiger>, client=0x18396f0) at
imap-client.c:879 No locals. #9 client_handle_input (client=client@entry=0x18396f0) at imap-client.c:891 _data_stack_cur_id = 3 remove_io = false handled_commands = false __FUNCTION__ = "client_handle_input" #10 0x00000000004164a2 in client_input (client=0x18396f0) at imap-client.c:933 cmd = 0x181db70 output = 0x183a120 bytes = 35 __FUNCTION__ = "client_input" #11 0x00007f174babd8f7 in io_loop_call_io (io=0x183a1f0) at ioloop.c:388 ioloop = 0x1808730 t_id = 2 #12 0x00007f174babe687 in io_loop_handler_run
(ioloop=ioloop@entry=0x1808730) at ioloop-epoll.c:220 ctx = 0x18093c0 list = 0x180adf0 io = <optimized out> tv = {tv_sec = 1799, tv_usec = 999100} events_count = <optimized out> msecs = <optimized out> ret = 1 i = 0 call = <optimized out> __FUNCTION__ = "io_loop_handler_run" #13 0x00007f174babd498 in io_loop_run (ioloop=0x1808730) at ioloop.c:412 __FUNCTION__ = "io_loop_run" #14 0x00007f174ba6ddf3 in master_service_run (service=0x18085c0,
callback=callback@entry=0x41eea0 ) at
master-service.c:566 No locals. #15 0x000000000040b06f in main (argc=1, argv=0x1808390) at main.c:400 set_roots = {0x426d00 , 0x0} login_set = {auth_socket_path = 0x1800048 "\001",
postlogin_socket_path = 0x0, postlogin_timeout_secs = 60, callback =
0x41f250 , failure_callback = 0x41ef80 ,
request_auth_token = 1} service_flags = <optimized out> storage_service_flags = <optimized out> username = 0x0 c = <optimized out>