Thank you for contacting Syncfusion support.
We have analyzed the issue and the issue “Exception throwing when showing the popup” has fixed and will include this issue fix in our next upcoming 2019 Volume 3 beta release which is scheduled to be available on mid of September. We appreciate your patience until then. We have provided the patch for this issue.
Please find the patch for the issue fix below.
Advanced approach – use only if you have specific needs and can directly replace existing assemblies for your build environment
Please find the patch assemblies alone from below location:
Clear NuGet cache by using the following link:
Assembly Version: 184.108.40.206
Please note that we have created this patch for version 220.127.116.11 specifically to resolve the following issue reported in this, and this fix will be included in our upcoming weekly NuGet release update which is scheduled to be available on mid of September.
Could you please check with this and revert us whether this solution meets your requirement?