# Threaded function throws no error

**URL:** <https://discourse.julialang.org/t/threaded-function-throws-no-error/80209>\
**Category:** New to Julia\
**Created:** [April 28, 2022, 12:42pm UTC](https://discourse.julialang.org/t/threaded-function-throws-no-error/80209 "2022-04-28T12:42:24Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![f.ij](https://avatars.discourse-cdn.com/v4/letter/f/8491ac/32.png) [@f.ij](https://discourse.julialang.org/u/f.ij)\
**Post date:** [April 28, 2022, 12:42pm UTC](https://discourse.julialang.org/t/threaded-function-throws-no-error/80209/1 "2022-04-28T12:42:24Z")

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Hi there,

I’m trying to build an application using the QML Julia package. I have a QML window open with a while loop in the background that is updating a display. I call this function using Threads.@spawn, because otherwise I cannot update the display (JuliaDisplay) in QML interactively. I’m also starting QML using the async\_exec() function. However, now I have the problem that if something in my background loop goes wrong, I get no error. The QML interface is still responsive, but the background loop dies, without me being able to see where the error occurred. How can I find out what went wrong in the background loop?

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<div class="post-metadata">

**Author:** ![f.ij](https://avatars.discourse-cdn.com/v4/letter/f/8491ac/32.png) [@f.ij](https://discourse.julialang.org/u/f.ij)\
**Post date:** [May 3, 2022, 11:47am UTC](https://discourse.julialang.org/t/threaded-function-throws-no-error/80209/2 "2022-05-03T11:47:03Z")

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I found someone else asking a similar question here:  
[Multithreading and “silent errors”](https://discourse.julialang.org/t/multithreading-and-silent-errors/78983)