[WPF] Exception: "object reference not set to an instance of an object"

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Last Updated: 07 Jun 2021 06:44 by ADMIN

Bartlomiej

Created on: 08 Apr 2021 11:24

Type: Bug Report

[WPF] Exception: "object reference not set to an instance of an object"

Hi,

We are unable to use TestStudio for WPF, when closing the window during recording we get an excpetion.

I tried and created simple wpf app in VS 2019 and get same results.

I attached a C# project as solution was to big.

Simple app is based on VS 2019 telerik for WPF project, created as blank.

Only code changed is adding a DispatcherUnhandledException on App class.

Handler:

private void OnDispatcherUnhandledException(object sender, DispatcherUnhandledExceptionEventArgs e)
        {
            if (e.Handled || e.Exception == null)
            {
                return;
            }
 
            e.Handled = true;
 
            MessageBox.Show(e.Exception.Message);
        }

Steps:

1) Create new project

2) Create new test for WPF

3) Configure to the WPF app exe file

4) Click record

5) After test studio is connected close the window.

Expected results:

Window get closed without any problems.

Actual results:

While closing the window exception is being thrown that we.

Attached Files:

wpf2-7z.zip

7 comments

ADMIN

Elena

Posted on: 14 Apr 2021 08:31

Hi Bartlomiej,

Thank you for your understanding once again. You can follow this item to get update on its status change or contact us back at any time.

Regards,
Elena
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Bartlomiej

Posted on: 13 Apr 2021 11:16

Hi,

I see no problem we can use older version and upgrade in the future.

ADMIN

Elena

Posted on: 12 Apr 2021 15:24

Hi Bartlomiej,

I am pleased to know that you managed to downgrade to the suggested previous version of Test Studio and you have no further issues with recording the tests.

I also hope that this could be a feasible workaround for you for some further time. The reason I am saying this is that we managed to investigate the issue on our end, and it turns out we can publish a fix at the earliest with our next release. This will come up in the upcoming months, so I hope you can postpone the upgrade of Test Studio to its latest version until the fix can be published.

Let me know in case this wouldn't work for you.

Thank you for your understanding in advance.

Regards,
Elena
Progress Telerik

Bartlomiej

Posted on: 12 Apr 2021 11:56

Hi Elena,

I can confirm that on version 2020.3.110.2 issue doesn't reproduce.

We will use that version.

ADMIN

Elena

Posted on: 09 Apr 2021 09:43

Hi Bartlomiej,

Thank you for getting back to me with these additional details for the actual application - the issue is critical for you.

We are already working on sorting the error in the sample and what causes this. I hope that until the end of next week we will be able to prepare a custom build with a fix applied.

In the meantime, if the matter is urgent, there are two possible workarounds we have identified. Please, note that both are optional and we don't necessarily need your feedback on these. So, if you don't have the time, you can skip them.

Here what it is - we identified that the sample app doesn't produce the error on each environment on our end. Having this in mind, you can try to use a different computer, if possible, one that is using different OS at least. Unfortunately, there is nothing particular that we can recommend, as the details, we managed to collect, are not quite consistent.

The other option you can test is to install a particular previous version of Test Studio - the sample app is not crashing if recording a test with Test Studio 2020 R3 (v.2020.3.110). I checked your licenses and can confirm you can download this from your Telerik account here (choose the correct version from the dropdown).

So, if you decide to downgrade to that previous version of Test Studio, please, keep in mind the following notes:

Uninstall the current Test Studio version from the Windows control panel.
Then download and install the previous version you have downloaded.

I remain available for any further queries you might have. And if not, I will get back to you when we can provide the custom build.

Thank you once again for your cooperation.

Regards,
Elena
Progress Telerik

Bartlomiej

Posted on: 09 Apr 2021 07:06

Hi Elena

Maybe to clarify, it happens on every pop up not only on main window. We are enable to close anything because we get exception.

1) does it prevents you from developing the test cases?

Yes, I have pop ups in my tool and when I close them I get exceptions and can't proceed with further test steps.

2) Are you able to start the test recording and execution after this crash when closing the app with the recorder attached?

For this simple App yes, for our tool we must close using task manager as it creates infinite loop of exceptions.

3)Do you see any further inconsistency in result of the crash?

Can't really tell, our validation wanted to use the tool to create automatic tests and they can't properly create one.

ADMIN

Elena

Posted on: 08 Apr 2021 15:25

Hello Bartlomiej,

I am sorry to know you are having troubles with the automation of the WPF application on your end and will be happy to assist further with this.

We managed to reproduce the same misbehavior on few environments on our end, and for other machines it worked fine. Anyways, I converted this ticket to a public bug report item listed on our feedback portal and the case will be further investigated from the engineering team.

I will appreciate if you share some details for the issue - does it prevents you from developing the test cases? Are you able to start the test recording and execution after this crash when closing the app with the recorder attached? Do you see any further inconsistency in result of the crash?

Thank you in advance for your cooperation.

Regards,
Elena
Progress Telerik