My app does not load due to the extension. How to remove an extension
in the designer do a right mouse click onto the x to delete it
example:

Taifun
This URL allows you to open AI2 to the Project List, without opening any project.
http://ai2.appinventor.mit.edu/?autoload=false
From that list, you can request Exports of Projects without trying to open them.
Upload the troublesome .aia here.
My app doesn't open at all to open the designer panel
Thanks, but you mean to upload my aia file here?
Yes, so we can try to fix it.
This does not appear to be an MIT AI2 project.
How to detect foreign aia files:
Open in 7zip, and zoom in on Screen1.scm in the src subdirectory.
Open the Screen1.scm file in Notepad++, and check its xml against the top sample's authURL.
In this sample comparison, the second Screen1.scm file fails the authURL check and has a higher version than AI2.
Plus, there is no extension in the aia provided!
(added to FAQ)
It's a component from the old Appybuilder server..
