# Error: Undefined Symbol: \_RegisterSuspendCallback when building for iOS

**URL:** https://qa.fmod.com/t/error-undefined-symbol-registersuspendcallback-when-building-for-ios/18050
**Category:** Unity
**Tags:** ios, unity
**Created:** [December 5, 2021, 5:16pm UTC](https://qa.fmod.com/t/error-undefined-symbol-registersuspendcallback-when-building-for-ios/18050 "2021-12-05T17:16:35Z")
**Posts on this page:** 1
**Showing post:** 2

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### Author: ![jeff\_fmod](https://yyz2.discourse-cdn.com/flex036/user_avatar/qa.fmod.com/jeff_fmod/32/1766_2.png) [@jeff\_fmod](https://qa.fmod.com/u/jeff_fmod)
#### Post date: [December 13, 2021, 2:10am UTC](https://qa.fmod.com/t/error-undefined-symbol-registersuspendcallback-when-building-for-ios/18050/2 "2021-12-13T02:10:03Z")

</div>

Sounds like the same issue as described [here](https://qa.fmod.com/t/link-issue-in-ios/17941), except I’m guessing you haven’t modified your XCode project at all?  
I have not been able to reproduce this error with your version, can you tell me a little more about your project? Are you using custom plugins, or anything like that?

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