# PX4/JMAVSIM Build error (return value 512)

**URL:** <https://discuss.px4.io/t/px4-jmavsim-build-error-return-value-512/18710>\
**Category:** Uncategorized\
**Created:** [September 22, 2020, 11:45pm UTC](https://discuss.px4.io/t/px4-jmavsim-build-error-return-value-512/18710 "2020-09-22T23:45:55Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![krystek](https://discuss.px4.io/letter_avatar_proxy/v4/letter/k/ba9def/32.png) [@krystek](https://discuss.px4.io/u/krystek)\
**Post date:** [September 22, 2020, 11:45pm UTC](https://discuss.px4.io/t/px4-jmavsim-build-error-return-value-512/18710/1 "2020-09-22T23:45:55Z")

</div>

Hi,

I am trying to run JMAVSIM on Windows 10. It worked for me before and then something happened when I tried to run it again. I uninstalled and reinstalled the PX4 Toolchain and have tried to run it again and keep getting this error. I have look at some stuff that it has something to do with bash, dash, but I don’t understand the lingo I’m pretty new to this. Here is the run error:

$ make px4\_sitl jmavsim  
[0/1] cd /cygdrive/c/PX4/home/Firmware/build/px4\_sitl\_defa…mware /cygdrive/c/PX4/home/Firmware/build/px4\_sitl\_default  
SITL ARGS  
sitl\_bin: /cygdrive/c/PX4/home/Firmware/build/px4\_sitl\_default/bin/px4.exe  
debugger: none  
program: jmavsim  
model: none  
world: none  
src\_path: /cygdrive/c/PX4/home/Firmware  
build\_path: /cygdrive/c/PX4/home/Firmware/build/px4\_sitl\_default  
empty model, setting iris as default  
SITL COMMAND: “/cygdrive/c/PX4/home/Firmware/build/px4\_sitl\_default/bin/px4.exe” “/cygdrive/c/PX4/home/Firmware/build/px4\_sitl\_default”/etc -s etc/init.d-posix/rcS -t “/cygdrive/c/PX4/home/Firmware”/test\_data  
INFO [px4] Creating symlink /cygdrive/c/PX4/home/Firmware/build/px4\_sitl\_default/etc → /cygdrive/c/PX4/home/Firmware/build/px4\_sitl\_default/tmp/rootfs/etc

| \_\_\_ \ \ \ / / / |  
| | _/ / \ V / / /| |  
| \_\_/ / \ / /_ | |  
| | / /^\ \ \_\_\_ |  
_| / / |_/

px4 starting.

INFO [px4] Calling startup script: /bin/sh etc/init.d-posix/rcS 0  
/cygdrive/c/PX4/home/Firmware/build/px4\_sitl\_default/bin/px4-alias.sh: line 42: `source’: is a special builtin  
ERROR [px4] Startup script returned with return value: 512

---

<div class="post-metadata">

**Author:** ![bresch](https://discuss.px4.io/user_avatar/discuss.px4.io/bresch/32/2343_2.png) [@bresch](https://discuss.px4.io/u/bresch)\
**Post date:** [September 28, 2020, 6:39am UTC](https://discuss.px4.io/t/px4-jmavsim-build-error-return-value-512/18710/2 "2020-09-28T06:39:00Z")

</div>

Hi @krystek ,  
This is a regression that was introduced recently and will be fixed soon, see [https://github.com/PX4/Firmware/issues/15795](https://github.com/PX4/Firmware/issues/15795)