# Exception in AWT-EventQueue-0 with SelectDropDownList

**URL:** <https://forum.universal-robots.com/t/exception-in-awt-eventqueue-0-with-selectdropdownlist/1541>\
**Category:** URCap Development\
**Tags:** java-error\
**Created:** [January 26, 2018, 8:57pm UTC](https://forum.universal-robots.com/t/exception-in-awt-eventqueue-0-with-selectdropdownlist/1541 "2018-01-26T20:57:57Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![anon16416181](https://avatars.discourse-cdn.com/v4/letter/a/5f8ce5/32.png) [@anon16416181](https://forum.universal-robots.com/u/anon16416181)\
**Post date:** [January 26, 2018, 8:57pm UTC](https://forum.universal-robots.com/t/exception-in-awt-eventqueue-0-with-selectdropdownlist/1541/1 "2018-01-26T20:57:57Z")

</div>

Hi!  
I’m using Polyscope 3.5.1. In my URCap, I’m updating the options of a `SelectDropDownList` based on some message received via TCP/IP. In some cases, I see the following error message:

 ![image](https://us1.discourse-cdn.com/flex020/uploads/universal_robots/original/1X/2df90440d96a9241ef09d7043eb16d1118d0a55e.jpg)

I’ve never seen it in 3.4.x.

One more clue: I’m using `setItems` method with a list of strings to update the list. Whenever an update is triggered, I update all the program nodes that are available (not just the one that has the command window opened).  
If I close the popup, everything seems to continue normally. It doesn’t seem like a serious bug, but it may be good to know the cause.

Any ideas?

Edit: I’m asking this here because all those lines in the stack trace aren’t coming from the URCap’s code.