# UE4 C++ crash when using multiple systems?

**URL:** <https://qa.fmod.com/t/ue4-c-crash-when-using-multiple-systems/16822>\
**Category:** Unreal Engine\
**Tags:** cpp\
**Created:** [February 28, 2021, 2:55am UTC](https://qa.fmod.com/t/ue4-c-crash-when-using-multiple-systems/16822 "2021-02-28T02:55:01Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![quandini](https://yyz2.discourse-cdn.com/flex036/user_avatar/qa.fmod.com/quandini/32/1964_2.png) [@quandini](https://qa.fmod.com/u/quandini)\
**Post date:** [February 28, 2021, 2:55am UTC](https://qa.fmod.com/t/ue4-c-crash-when-using-multiple-systems/16822/1 "2021-02-28T02:55:01Z")

</div>

Hi, Whenever I stop PIE in the unreal editor I get `Unhandled Exception: EXCEPTION_ACCESS_VIOLATION reading address 0x00000030`. when using the rider for UE4 debugger it just repeats the same message to me and doesn’t point me in any direction. I am using multiple systems that share DSP effects and I thought that might be the issue but nope that seems to be working fine. even trying to release the 2nd system I get the crash. this also seems to be a lot less stable and consistent in shipping build with it crashing every other time I stop the recording of the 2nd system. I have also had the debugger in the past scream at me saying ‘still in mixer thread’ but have not seen the issue after revising my code. does anyone have a clue why this might be a thing?

ue4 version: 4.25.4  
FMOD version: 2.01.07

---

<div class="post-metadata">

**Author:** ![cameron-fmod](https://yyz2.discourse-cdn.com/flex036/user_avatar/qa.fmod.com/cameron-fmod/32/261_2.png) [@cameron-fmod](https://qa.fmod.com/u/cameron-fmod)\
**Post date:** [March 5, 2021, 5:32am UTC](https://qa.fmod.com/t/ue4-c-crash-when-using-multiple-systems/16822/2 "2021-03-05T05:32:53Z")

</div>

Depending on the logging level of FMOD, set in the FMOD UE4 Plugin settings, you may be able to get some more logging from FMOD.

Any logs or a repro of the problem would be helpful in figuring out the cause.

---

<div class="post-metadata">

**Author:** ![quandini](https://yyz2.discourse-cdn.com/flex036/user_avatar/qa.fmod.com/quandini/32/1964_2.png) [@quandini](https://qa.fmod.com/u/quandini)\
**Post date:** [April 18, 2021, 8:37am UTC](https://qa.fmod.com/t/ue4-c-crash-when-using-multiple-systems/16822/3 "2021-04-18T08:37:20Z")

</div>

sorry for taking a long time to reply. I found out what my issue was. I have 2 systems and I switch between them often and I thought I should use the same DSP effect to make it easy to manage DSP effects. turns out sharing DSP effects on systems causes issues 🤦‍♂️

I have resolved the solution now by having a second DSP for the second system.