In ArcGIS Web AppBuilder, adding multiple copied images that have been resized in Microsoft Word using Ctrl P causes the About and Splash widget editors to stop responding.

対処法

1. Click the Add Image button  to add an image by browsing. The size of the image must not be over 1,024K; otherwise, a warning message is displayed. 
2. Use Paint 3D or Photoshop to create a JPEG (For the best result, the image must be 160 pixels wide by 90 pixels high).
3. Save the JPEG and use the tool in the Splash widget toolbar to insert each image.

Refer to the following link for more information:

https://doc.arcgis.com/en/web-appbuilder/create-apps/widget-splash.htm 

再現の手順