# Nucleo-F439ZI FreeRTOS + TCP always returns a byte count of 0xfffffff4

**URL:** <https://forums.freertos.org/t/nucleo-f439zi-freertos-tcp-always-returns-a-byte-count-of-0xfffffff4/22121>\
**Category:** Libraries\
**Tags:** debug\
**Created:** [December 22, 2024, 8:13pm UTC](https://forums.freertos.org/t/nucleo-f439zi-freertos-tcp-always-returns-a-byte-count-of-0xfffffff4/22121 "2024-12-22T20:13:42Z")\
**Posts on this page:** 1\
**Showing post:** 5

<div class="post-metadata">

**Author:** ![ActoryOu](https://d3iykfbgfh8zhg.cloudfront.net/user_avatar/forums.freertos.org/actoryou/32/2880_2.png) [@ActoryOu](https://forums.freertos.org/u/ActoryOu)\
**Post date:** [December 23, 2024, 3:26am UTC](https://forums.freertos.org/t/nucleo-f439zi-freertos-tcp-always-returns-a-byte-count-of-0xfffffff4/22121/5 "2024-12-23T03:26:21Z")

</div>

> [@sensor\_guru](#):
>
> I’m able to ping the Nucleo fine from the PC, verified through Wireshark (can’t upload pcap as I’m a new user), getting a successful [SYN}, [SYN, ACK] and [ACK]. When I go to send a message of 0xDE AD BE EF to the Nucleo Wireshark shows it keeps trying a [TCP Retransmission].

Hi @sensor_guru,  
The value 0xfffffff4 represents `-pdFREERTOS_ERRNO_ENOMEM` , which prvRECVWait returns when unable to allocate memory for the TCP stream buffer. For helpful advice on this issue, please see: [FreeRTOS TCP/IP pdFREERTOS\_ERRNO\_ENOMEM (Nucleo-F767Zi)](https://forums.freertos.org/t/freertos-tcp-ip-pdfreertos-errno-enomem-nucleo-f767zi/9219).

Thank you.

---

_[View the full topic](https://forums.freertos.org/t/nucleo-f439zi-freertos-tcp-always-returns-a-byte-count-of-0xfffffff4/22121)._