Home Bug in ComboBox of UWP Apps when using Custom Styles

Bug in ComboBox of UWP Apps when using Custom Styles

I’m investigating a weird issue for some of my app users since a while already, which I’m not able to reproduce on my PC, Surface tablet or Lumia phones. However, in the reviews of my Action Note app, I can read that some users seem to have troubles to open the settings page. First, I thought these are wrong reports. But after reading it a couple of times from different users made me thinking. And at least after I received the first bug report via Email, I realized this requires a closer look. After some detailed analysis I could figure out that these crashes must be related to the <ComboBox /> control. But I could not find anything useful that could help to resolve this problem.

After even more problem analysis, debugging and testing, I could finally narrow down that the root cause of the problem: Custom Styles used in context of a ComboBox. It even does not matter how this style is defined. Even using the generated default style from Microsoft Blend ends up with the same effect. Consequently, there seem to be only two options left: a.

  1. Use a ComboBox without any Custom Style
  2. Use a completely different control

Furthermore, I could figure out the following:

  • The problem does not seem to appear on Windows 10 Mobile devices
  • Only a few users on Windows 10 PC are affected
  • It seems only PC users are affected that installed Windows 10 via update, instead of doing a clean installation

Consequently, the use of <ComboBox /> in a Windows 10 UWP app requires attantion at the moment, as it can very unexpectedly cause instability. More details and progress of resolving this issue can be followed in my thread in MSDN.

Edit: It looks like I was indeed looking into some sort of nasty bug deep down in the Universal Windows Platform:

@Benjamin Sautermeister,

It’s really nice that you post the research result to here. I’ve purposed your answer since I think it will also be good for other customers who meet the same problem.

Best regards, Barry

This post is licensed under CC BY 4.0 by the author.