> > [dfe01,INFO] Slow control equipment initialized
> > dfe: src/midas.c:838: cm_msg_flush_buffer: Assertion `rp[3]=='_'' failed.
> > if I remove line 838 from midas.c (fixing message length) the problem disappear...
> 
> Thank you for reporting this problem.
> 
> It is very strange, the check is for message start "MSG_", why "M", "S" and "G" are there
> but "_" is missing? And you remove the check for "_" and the rest of the message is also okey?
> Very odd.

if I remove the check for "_" then the first message is empty and next messages are ok...
If I don't remove the check the frontend fails at start and I find these lines in midas.log:

14:46:29.719 2019/03/19 [dfe01,INFO] Program dfe01 on host lxaria02 started
14:46:29.731 2019/03/19 [dfe01,INFO] Dome FE initialized
14:46:29.737 2019/03/19 [dfe01,ERROR] [system.c:4709:recv_tcp2,ERROR] unexpected connection closure
14:46:29.737 2019/03/19 [dfe01,ERROR] [midas.c:12814:recv_event_server,ERROR] recv_tcp2(header) returned -1
14:46:29.737 2019/03/19 [dfe01,ERROR] [midas.c:14699:rpc_server_receive,ERROR] recv_event_server() returned -1, abort
14:46:29.737 2019/03/19 [dfe01,TALK] Program 'dfe01' on host 'lxaria02' aborted
 
> You can also add this code "assert(4+3*sizeof(int)+len < 1020)" in cm_msg_buffer() right before
> rb_increment_wp() - it this assert fails, we definitely determine that we have a buffer overflow.

I added assert you suggested in cm_msg_buffer() function before rp_increment_wp() and 
result is always the same at same line:

[dfe01,INFO] Dome FE initialized
Dome0001-rc:
[dfe01,INFO] Slow control equipment initialized
dfe: src/midas.c:839: cm_msg_flush_buffer: Assertion `rp[3]=='_'' failed.
Aborted

Regards,
Gennaro