Hi,
Correction.
The steps used here are not the steps I took.
There is NO modifying anything, there is no creating or adding custom widgets..
Reproduce the bug using the following steps after signing into WABde
1. Create New
2. select Default and press NEXT
3.Title = AppTEST Description = BUG Test
4. DO NOTHING
5. Click on "Web AppBuilder for ArcGIS to go back
6. In the WAB List 'Download' AppTest (save to a convenient file drive)
7. On the AppTest.zip file >> right click Extract All...
8. Explore into the unzipped AppTest Directory
9. Highlight all items and right click Send To.. Compressed (Zip) Folder
10. Whatever the name of the zip turns out to be...remember its location
11. in WABde >> Import >> Import from my computer
12. Select the fresh zipped app.
13. Receive "Invalid App" Prompt.