Unable to write to alert pipe - Permission denied!

Hello,

Centos 6.9, Asterisk 14.6.

I have one sip provider called “TEL”. When smb calls, after hangup CLI says:

ERROR: channel.c:1181 __ast_queue_frame: Unable to write to alert pipe on SIP/tel-00000000 (qlen = 0): Permission denied!

What does it mean? Can someone know what is a reason?

Thank You,
Michal

It’s an internal error that should not happen.