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Object Reference Bug

Hi team, 

I'm experiencing another issue with my control. Steps to reproduce the bug on my branch (happens on the others too): 

1) Create new task in a column
2) Move task to any other column
3) Try to delete the task

If you clone, or download this branch: https://github.com/hjohnson12/KanbanBoardUWP/tree/update_cardsdesign


That should reproduce the bug. I get a System.NullReferenceException: 'Object reference not set to an instance of an object.' and I've stepped through each part of my code and everything seems to be correct. When I look at the local $exception, I see things showing up for SfKanban DLL's and files, so I'm wondering if that has something to do with it, maybe? 

In the image included with this thread, you'll see at the point where it breaks is at Tasks.Remove(model). The previous line gets the previousCount, which is 1, as expected. Once it goes to the next line (line 278), Tasks.Count still holds 1, but once the line is executed it breaks; BUT, if you hover over Tasks, you'll see that its count is 0 now. 

So, it removes it, but then gets a null reference exception saying instance not set, when my model is definitely initialized and has data in it 😄

It's odd, I know. If you need any additional context, please let me know. I tried for a few days debugging, setting breakpoints, testing locals and watches, adding extra code, and nothings solved it. Hoping your team will notice something I wont :-) 

14 Replies

HU Hunter July 28, 2019 02:01 PM UTC

I can verify that it is happening on every single one of my branches as well, including master (although master is out of date at the moment, it's still doing it with those old changes before I made a bunch of new ones). The branch I linked in the above post is the most up to date. Here is the values when the exception happens: 


HU Hunter July 28, 2019 05:09 PM UTC

This is also the stack trace for the above exception. 

LR Lakshmi Radha Krishnan Syncfusion Team July 31, 2019 03:43 AM UTC

Hi Hunter,


We were able to reproduce the reported issue in the provided sample. But, we have checked the same issue with separate sample and the reported issue is not reproduced in our sample. We have attached the tested sample. Now, we are checking the sample you have provided. So, we need one more day to validate the sample, we will update you the status in one business day on July 31st, 2019.


TestedSample: https://www.syncfusion.com/downloads/support/directtrac/general/ze/KanbanSamp262787148



Lakshmi R.


HU Hunter July 31, 2019 03:48 AM UTC

Hi Lakshmi, 

Thank you for your reply! :) 

I will take a look at your provided sample in a few hours after work! I appreciate the feedback and you looking into this further 🙂

MK Muneesh Kumar G Syncfusion Team July 31, 2019 11:00 AM UTC

Hi Hunter, 
Thanks for your patience.

We can reproduce the issue (Null reference exception while deleting the card). We have confirmed this as an issue and logged bug report. We will include the patch for this issue on August 13th, 2019 weekly nuget. You can track the bug status from the below link.  
If you have any more specification/precise replication procedure or a scenario to be tested, you can add it as a comment in the portal link above. We appreciate your patience until then.   
Muneesh Kumar G.   

HU Hunter July 31, 2019 12:06 PM UTC

Hi Muneesh, 

I appreciate checking this out! If I find anything further procedure wise, I'll make sure to let you know!

I'm curious though, were you able to find the root of the problem? I checked many times but was unable to 🤔 (Besides that null error. Just didn't know what was throwing it)

MK Muneesh Kumar G Syncfusion Team August 1, 2019 06:53 AM UTC

Hi Hunter, 
This issue occurs due to the dragged card does not added to inner collection of particular column. Hence it does not available while trying to remove from that column, it throws the reported null reference exception.

As we said in our previous update, the patch for this issue will be available on August 13
th, 2019 weekly nuget.  
Muneesh Kumar G.   

HU Hunter August 1, 2019 12:50 PM UTC

Hi Muneesh, 

Thank you for you and your teams help investigating these issues. I'm sorry we've came across many issues along the way with the database and collection updating issues, hoping us solving them will help others out in the future! 

Also, once this patch is released, as well as the one from thread 145994, I should be nearly done with the app and issues will be all solved. Hope I haven't been a pain! :) 

MK Muneesh Kumar G Syncfusion Team August 1, 2019 01:22 PM UTC

Hi Hunter, 
We will merge both fixes in mentioned August 13th, 2019 weekly nuget.  We will let you know once it gets rolled out.  
Muneesh Kumar G.   

HU Hunter August 1, 2019 01:23 PM UTC

Awesome! Thanks so much team. I really appreciate it. 

MK Muneesh Kumar G Syncfusion Team August 2, 2019 06:07 AM UTC

Hi Hunter,  
Thanks for your update.  
Please let us know if you have any other queries.  
Muneesh Kumar G.   

MK Muneesh Kumar G Syncfusion Team August 13, 2019 05:15 PM UTC

Hi Hunter,  
We are glad to announce that our Weekly NuGet (v17.2.0.41) is rolled out. We thank you for your support and appreciate your patience in waiting for this release.   
Weekly NuGet Packages(v17.2.0.41) were published in nuget.org( https://www.nuget.org/profiles/SyncfusionInc). 
Please get in touch with us if you would require any further assistance.    
Muneesh Kumar G.    

HU Hunter August 14, 2019 03:16 AM UTC

Hi Muneesh!

Thank you for the update. After including the latest nuget package today and doing further testing/additions, I have not ran into the bug again! 😁

I thank you and your team very much for your support, samples provided, and patience with the bugs and questions for my application. It's been extremely helpful and if I have any additional questions upon finishing it I will definitely reach out. 

Again, thank you very much for your support!!

Best Regards, 

MK Muneesh Kumar G Syncfusion Team August 14, 2019 04:30 AM UTC

Hi Hunter,   
Thanks for the update. 
We are glad to know that the given solution works. Please let us know if you need any further assistance. 
Muneesh Kumar G. 

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