<!-- Thank you for reporting a bug in OpenSIPS! In order for us to understand better the issue you are facing, kindly provide all the available information you have about this bug, according to the template below --> **OpenSIPS version you are running** <!-- paste below, inside the ticks block, the output of the `opensips -V` command --> ``` [root@box ~]# opensips -V version: opensips 3.4.5 (x86_64/linux) flags: STATS: On, DISABLE_NAGLE, USE_MCAST, SHM_MMAP, PKG_MALLOC, Q_MALLOC, F_MALLOC, HP_MALLOC, DBG_MALLOC, FAST_LOCK-ADAPTIVE_WAIT ADAPTIVE_WAIT_LOOPS=1024, MAX_RECV_BUFFER_SIZE 262144, MAX_LISTEN 16, MAX_URI_SIZE 1024, BUF_SIZE 65535 poll method support: poll, epoll, sigio_rt, select. git revision: 6beb906e5 main.c compiled on 01:49:20 Apr 19 2024 with gcc 8 ``` **Describe the bug** append_to_reply not working when t_reply_with_body is used inside a failure_route block. Only the body is present in the reply. **To Reproduce** <!-- Steps to reproduce the behavior: Example: 1. Start OpenSIPS 2. Start traffic with special headers 3. Inspect traces 4. Notice the `X-Custom-Header` has wrong format --> ``` failure_route[local_reply] { t_reply_with_body(404, "Not Found", "a b c"); append_to_reply("Foo: bar\r\n"); ``` **Expected behavior** <!-- A clear and concise description of what you expected to happen. Example: the expected `X-Custom-Header` header should be sip:user@contact --> A sip reply with Foo: bar header and a body with content "a b c". **Relevant System Logs** no errors found in the opensip log. **OS/environment information** - Operating System: Almalinux 8 - OpenSIPS installation: official rpm packages A similar issue was [fixed](https://github.com/OpenSIPS/opensips/issues/1632) in the past for request route