Looks pretty well intact, loads without complaint - I think it must be pretty close to the original state before the issue began. In particular, when I tried to rescue the file (copy-paste incrementally to a new file) I had to remake the zero4D and initGPS procedures - however, after save, logout, login, load - those procedures had disappeared.
What did you find in Screen1.bky?
Don't know how this happened, but we don't have ListView event Click and by just renaming to AfterPicking everything started to work..
P.S. therefore you get this
That's a good spot. How on earth that could happen is a bit of a mystery - perhaps a 'Click' extension that was subsequently removed. I think a lot of the more recent extensions could be more robust.
Some lessons to learn Elson:
Keep regular incremental backups on your PC drive, especially before any major change/addition. I save a backup every 15 minutes.
Do not spam us!
Thank you very much Boban. You guys have been a solid help. 
Chris, I tried to use the following extension for listview and then I changed it back to the original ListView component in App Inventor and that's when this error may have occurred.
com.sumit1334.listview.aix (36.8 KB)(extension I used and then removed)
This has been a good learning curve for me and Thanks again guys.
..... that may have been for the 'original' ListView component, it has recently had a huge update.
Neither the built-in list view nor this extension reference the existence of a Click event. I wonder if some interplay between either the backpack or copy/paste functionality, in combination with a Button or other component with a Click handler had a name collision and the failure mode is the result we see here.
I'm currently at a loss for how to come up with a good sequence of events that would result in a project in this state.
If you look up the filename for that extension in Google, it may say differently!!
This leads to a different confusion!!
If there is any update to the original components in AppInventor, do I have to do it manually from my end?
Possible that a 'Click Extension' was initially used but then deleted?
.... the extension has a Click event
It looks like a nice extension, has a few more advanced features. However, I just tried it in a new Project - causes the Backpack to fail - Scenario:
Edit: Even if the extension is deleted, the Project is now corrupted.
The author if the extension @iamwsumit might want to check...
Probably it is not a good idea to use the same name for an extension to avoid conflicts like this?
Taifun
That's a good point, though the AI2 LV was "ListView1" and the Extension arrives as "ListView2". You should be able to have a standard LV and a Custom LV on the same Screen IMO.
Yes, but most probably different component/extension names are necessary...
My guess is, if @iamwsumit renames the extension to something else, for example Sumit1334Listview, then the issue is gone... magically...
Taifun
I was able to reproduce that scenario, see post #20.
It may be only a small issue from the extension perspective, the developer may not have expected a Standard ListView to be on the same Screen. It seems to be that deleting the extension is not 100% successful - not sure about that though.
I think you are right!
Not sure what you mean Elson. The AI2 ListView is a built-in component. Example:
ListViewAdd.aia (4.6 KB)
I understand that AI2 ListView is built-in.
This statement of yours raised the confusion about the downloadable extension and update in the original component. I thought I will have to manually update the built-in components when you said that "that may have been the original ListView component", when I never have to download a built-in component.
But, thanks for the example.
Extension having the same name as a built-in component could be the prime cause of this glitch.@iamwsumit
Often, extensions enhance existing components rather than delivering a complete replacement - hence my comment. At that time, I had not seen the extension (indeed, I had never heard of it until now, probably because it is not in the AI2 list of extensions but on Kodular's site).
I hope the error can be fixed easily - the basis of the extension is similar to the AI2 built-in component, but with a lot of more advanced features.
Yes, surely it is not. I already updated it a very long time ago in V2.
- Extension has renamed to
CustomListViewfromListViewas it was causing error while dragging the list view component. It may break your whole blocks. So kindly make a backup of the older project please. It was necesary to change the extension name.
Unfortunately, this extension is not fully compatible with AI2.
Read here:
You can give V3 a try:
Sure, you just need to call the class name something different. An example is the WebViewer component and the CustomWebViewer extension. The original extension development instructions encouraged this by having people build the extension alongside the App Inventor components so there was never any question that the name had to be different (you couldn't have two ListView.java files in the same folder...).
Internally, App Inventor keys off of the class name so creating extensions that collide with built-in App Inventor components with different signatures is a recipe for disaster.
