FRACK!, Failed assertion user_data is NULL

I previously posted in this forum a problem that we occasionally have with a pbx with asterisk 16, (16.8). About every 15 to 20 days it happens. This is the backtrace obtained:

[May 20 15:46:33] ERROR[4657][C-0000615b] rtp_engine.c: FRACK!, Failed assertion user_data is NULL (0)
[May 20 15:46:33] ERROR[4657][C-0000615b] : Got 14 backtrace records
0: asterisk(__ao2_lock+0x207) [0x55b92be5aec7]
1: asterisk(ast_rtp_instance_read+0x33) [0x55b92bf498a3]
2: /usr/lib/asterisk/modules/chan_sip.so(+0x23826) [0x7effe98b4826]
3: asterisk(+0xc1857) [0x55b92beb2857]
4: /usr/lib/asterisk/modules/app_dial.so(+0x748e) [0x7effe373648e]
5: /usr/lib/asterisk/modules/app_dial.so(+0xb197) [0x7effe373a197]
6: /usr/lib/asterisk/modules/app_dial.so(+0xd559) [0x7effe373c559]
7: asterisk(pbx_exec+0xc9) [0x55b92bf39d39]
8: asterisk(+0x13bf31) [0x55b92bf2cf31]
9: asterisk(+0x13e322) [0x55b92bf2f322]
10: asterisk(+0x13f97b) [0x55b92bf3097b]
11: asterisk(+0x1c26bc) [0x55b92bfb36bc]
12: /lib/x86_64-linux-gnu/libpthread.so.0(+0x74a4) [0x7f003a5b74a4]
13: /lib/x86_64-linux-gnu/libc.so.6(clone+0x3f) [0x7f00391c1d0f]

Any ideas? What could be happening?
Thank you.

What’s happening is that you are trying to debug something for which most of the debugging symbols have been stripped by the building or installation process,and you seem to have backtraced a different thread from the one that raised the assertion.

The actual message indicates either memory corruption or that a data structure contained some information in a context where it should not have done so, as the result of a logic error in the code.