Hi,

I'm using several Telerik controls in my Xamarin.Forms app, like RadListView, RadButton, RadExpander etc. The issue I'm facing is when I scroll RadListView, the app crashes with following exception: 

"Scrapped or attached views may not be recycled. isScrap:false isAttached:true  xamarin.forms"

I tried searching a lot about this issue but there are only native solutions available, and there is no native code used in Xamarin.Forms project. I'm unable to find any solution for this crash on any Xamarin Forum or blog.

It would be really appreciable if someone can look into this issue and guide me what am I doing wrong?

 

Thanks & Regards,

Nidhi Sood

Hi Nidhi,

If you are using Xamarin.Forms 4.0, we do not have full support for 4.x yet. There are some view-related issues that we will have fixes for in the upcoming R2 2019 SP1 release. Until then, to resolve this, update the version of Xamarin.Forms to 3.6 (you can use the latest 3.6 version).


Further Investigation

If you are not using XF 4.0, then I'm unable to determine the cause of what you're experiencing without investigating directly. Especially with this kind of error, we'll need an isolated reproducible application to debug directly. 

Please reply back with an isolated, runnable, example that causes the error. List the steps I need to take to reproduce the error. Although the reproducible project will have the SDK specifics in it, we will also need specifics from you about the runtime (device, the OS version ,etc).

Note that you cannot attach a ZIP to a forum thread, so you'll need to host it somewhere like Dropbox or One:Drive. Important: Please delete all the bin and obj folders from every project so that you do not accidentally redistribute a licensed version of the Telerik assemblies to other people visiting this thread) 

Once I get this reproducible from you, I will be able to dig deeper. I will also forward it to development team for additional investigation.

Regards,
Lance | Technical Support Engineer, Principal
Progress Telerik

Hi Lance,

Thanks for your quick response!

Yes, I'm using Xamarin.Forms 4.0.0-pre7 and making the app for tablets, with latest OS. The problem is I cannot downgrade the version from 4.0 to 3.6, as it will break my code and also we have used some of the new controls from 4.0 version. So, it won't be feasible to change the code close to completion of the project. 

So, if you can suggest some other workaround to handle/avoid this crash that would be really helpful as I have an important demo scheduled for tomorrow.

 

Thanks & Regards,

Nidhi Sood

 

 

Hello Nidhi,

I may have some news for you, but I'm not it's good news sure until you try it. Before I go into that, please be patient with me while I explain a few topics and provide some insight into dependency alignment.


Licensed User

I noticed that you have no active support, this is completely fine and is usually an indication that a previous license has expired. However, in your case, you have never downloaded or received a license (trial or paid) for any Telerik product with this account. This means you should not have access to, or be developing with, Telerik UI for Xamarin.

It is common that a company will purchase the license and you are the developer. If this is the case, please contact the account holder and have them assign you as the Licensed User. It literally takes 15 seconds to switch the license to your account (they will remain the owner and can switch users at any time).

1. Go to Manage Licensed Users Portal
2. Unassign the license from the company account (they will remain the owner of the license)
3. Assign the license to you (using your email)

This will allow you to download and  install newer versions and open priority support tickets. Okay, let's move onto the technical topics!


Prerelease and Latest Version Support

UI for Xamarin will never officially support a prerelease or experimental version of Xamarin.Forms. The officially supported minimum version must be a stable release from Microsoft. Although newer versions usually work, we do not build with or test with those newer versions.

It's important to remember that when UI for Xamarin R1 2019 was released, Xamarin.Forms 4 was not released yet. Thus, UI for Xamarin 2019.1.x was released with XF 3.6 support. When XF 4 was pushed into the stable channel, it was a major release with significant breaking changes from Microsoft. 

We will try to match the next major Telerik release with the latest version of Xamarin.Forms (the next major release is 2019 R3). We may or may not use XF 4.0 as the version of XF that we build on depending on what kind of problems that brings to our users who still need XF 3.6.

Utimately, we will avoid bumping the minimum version of XF in the middle of a release (i.e. 2019 R2 SP1) unless it is absolutely necessary.


2019 R2

Let's discuss the current UI for Xamairn release, 2019 R2. It has the minimum version of Xamarin.Forms set to 3.6.  Using newer "officially unsupported" version of Xamarin.Forms usually works, but there are always breaking changes from Microsoft when they bump the major version number (i.e. 2.x -> 3.x -> 4.x) and we cannot guarantee it will.


2019 R2 SP1

Today was a big release for 2019 R2, the first Service Pack (aka SP1). We have many fixes for XF 4 problems in this release. I recommend trying it to see it if it fixes your issue.

If it doesn't then I ask that you follow my previous instructions on providing a reproducible. This will allow me to get the developers involved and work on a fix for the next service release (we do smaller service release about once a month). 


Fixing Problems in XF 4.x

In the cases that there is a problem, this is when we ask that you provide an isolated, clear reproducible. With this test project, we can isolate the issue and include a fix in a service release (even though we don't officially support that version).

This is what has been happening in the past few service releases, there were a few problems with breaking changes in XF 4 that we could resolve, while keeping XF 3.6 as the minimum version.


Wrapping Up

Thank you for your patience and understanding while reading my explanations. I hope it helps clears things up and you understand how the release cycle is aligned.

If today's release doesn't help, please consider opening a Bug Report Ticket with the reproducible attached (important!) so that we can work on getting a fix out as soon as possible.

Regards,
Lance | Technical Support Engineer, Principal
Progress Telerik

Hi Lance,

Thank you so much for explaining things so well. Let me try the new release and see if it fixes my problem. Then, I'll get back to you if it doesn't!

Thanks & Regards

Nidhi Sood

 

Hi Lance,

Hope you are doing good!

I got the licensed account from my client and I checked there the license just expired this month. And I couldn't find any latest version for Xamarin UI. Can you help me out with this?

Thanks & Regards,

Nidhi Sood

 

Hi Nidhi,

I checked your account, however this one hasn't been assigned to any licenses. Did they use a different email address? Either you or they can contact Sales to get this settled once and for all.

Telerik licensing is perpetual, once you've had a license to a set of releases, you will always have that access even if the support expires (e.g. earlier this month). If you log into Telerik.com with the account that has the licence, the account will show all the versions during the time the license was active.

As an example, if you go to the UI for Xamarin downloads page, you can see those version in the dropdown:



The same is true for the Telerik NuGet server. It uses the licenses for the account that is logging into the server and will list the versions for the time-frame there was a license.

Ultimately, even as of the latest release 2019.2.619, there still could be issues with XF 4.x as we have not officially announced support. It could still be that there is a problem in your specific setup that we haven't seen yet. We're fixing XF 4 reported issues as they come in so that you can unofficially still use it.


Regards,
Lance | Technical Support Engineer, Principal
Progress Telerik

Hi Lance,

This is not the licensed account, it's client's account from which he bought the subscription which got expired. I tried creating a new support ticket from that particular account but due to license expiration, I was unable to do so. 

Also, I checked the version of Telerik UI for Xamarin, and got the new one now.

Thanks for your support! I may need further assistance & support from your end, but let me try this latest version first.

Regards,
Nidhi Sood