# URControl: Unknown Mutex::Mutex() calling exit (-1)

**URL:** <https://forum.universal-robots.com/t/urcontrol-unknown-mutex-mutex-calling-exit-1/25865>\
**Category:** URCap Development\
**Created:** [December 28, 2022, 8:59am UTC](https://forum.universal-robots.com/t/urcontrol-unknown-mutex-mutex-calling-exit-1/25865 "2022-12-28T08:59:34Z")\
**Posts on this page:** 1\
**Showing post:** 4

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**Author:** ![felix.green](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.universal-robots.com/felix.green/32/6215_2.png) [@felix.green](https://forum.universal-robots.com/u/felix.green)\
**Post date:** [May 15, 2024, 3:14pm UTC](https://forum.universal-robots.com/t/urcontrol-unknown-mutex-mutex-calling-exit-1/25865/4 "2024-05-15T15:14:33Z")

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I am on an M3 Macbook Pro. I can run URsim, but the controller stays off and can’t be turned on. I discovered this error when digging through logs at: `ursim/URControl.log`.

It seems to be related to this issue:

> [@URSim on M1 Macbook](https://forum.universal-robots.com/t/ursim-on-m1-macbook/14668/6):
>
> Does the URControl run ok? When you open the URSim, is there a No Controller in the bottom left?

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