UWP Memory leaks on Navigation Page - xaml

I have try to develop UWP App, but i have find many problems with memory leaks, using simple project when switch from page to other page the memory is not free using visual studio diagnostics. Other user have same problems?
for reproduce the problems i have prepared a sample project
http://www.fasthomestore.it/UWPNavigation.zip
Compile, start project, start visual studio diagnostic, wait 30 minutes, the memory increase continually

You may need to set the NavigationCacheMode to Required or Enabled, by default, this value is Disabled which means
The page is never cached and a new instance of the page is created on each visit.
public SecondPage()
{
this.InitializeComponent();
this.NavigationCacheMode = Windows.UI.Xaml.Navigation.NavigationCacheMode.Required;
...
//this.Unloaded += SecondPage_Unloaded;
}
private void OnTick(object sender, object args)
{
//_timer.Stop();
...
}
This will not create a new instance each time the page navigate. More details please reference Page.NavigationCacheMode property.

Related

Xamarin.Forms Communication Between Two Pages Within Same App on Different Devices

Technologies, frameworks and devices I'm using:
Framework: Xamarin.Forms
IDE: Visual Studio 2022
Physical Device (smartphone): Zebra TC26 (Android 10)
Physical Device (smartwatch): Samsung Galaxy Watch4 (Android 11)
Problem definition
Currently I have a test Xamarin.Forms project that consists of two different UIs (XAML files):
User Interface 1: HomePage.XAML - This screen should be displayed on the smartphone
User Interface 2: WatchScreen.XAML - This screen should be displayed on the smartwatch
With code below I make sure HomePage.XAML is deployed to a smartphone and watchscreen is deployed to a smartwatch:
Page homePage = new NavigationPage(new HomePage());
// BuildVersionCodes.R is a reference to Android version 11 (mostly now used by Wear OS 3.x)
if (Build.VERSION.SdkInt == BuildVersionCodes.R)
{
// SM-R870 is a reference to the Samsung Galaxy Watch4
// Note: This is needed to ensure the UI is specific to the UI of a smartwatch
if (Build.Model == "SM-R870")
{
Page watchScreen = new NavigationPage(new WatchScreen());
MainPage = watchScreen;
}
}
else
{
MainPage = homePage;
}
Now I want to make these pages on different devices communicate with each other. HomePage.xaml exists within the main Xamarin.Forms project as well as WatchScreen.xaml.
The way I want them to communicate with each other is by sending a message or something. A Xamarin.Forms project also comes with a native project. In this native Xamarin.Android project I try to retrieve inside the MainActivity.cs the button that exists within the main project by using (in WatchScreen.xaml this button exists and in WatchScreen.xaml.cs I have a method that gives this button back).
Method in WatchScreen.xaml.cs that gives button back:
public Button GetSendButtonFromWearableUI() => btnSendMessage;
In MainActivity.cs I get this method by using:
Button button = (App.Current.MainPage.Navigation.NavigationStack.LastOrDefault() as WatchScreen)
.GetSendButtonFromWearableUI();
Whenever I click on the button by doing this:
button.Clicked += delegate
{
SendData();
};
Some data should be sent from MainActivity.cs and catched by HomePage.xaml and displayed on it. I tried several approaches but I didn't succeed in achieving what needs to happen.. Therefore, I'm wondering if you guys could help me out with this and would be much appreciated.
In the meantime I've been investigating this issue and came up with a solution. Follow steps below to get the same result. To make this solution work I've combined the Wearable Data Layer API from Google and MessagingCenter from Microsoft.
Also the example below shows only the communication from the smartwatch to the smartphone. In order to reverse processes you can put the send button on the HomePage instead of the smartwatch screen and make sure to subscribe to the correct messages.
One last note: keep in mind that code used below from Google is deprecated but it still works...
References used to make this work:
Syncing Data Between Wearable and Handheld Devices Using Xamarin in Android
Installed dependencies on the Xamarin.Android project within Xamarin.Forms project:
Xamarin.Android.Support.v4
Xamarin.GooglePlayServices.Base
Xamarin.GooglePlayServices.Wearable
MessageKeys.cs
This class is used to declare message keys that are being used to send and receive messages between devices.
public class MessageKeys
{
public const string Smartwatch = "Smartwatch";
public const string Smartphone = "Smartphone";
}
Xamarin.Forms (Base project) - App.xaml.cs
In the App.xaml.cs, as pointed out earlier, I'm making sure the wearable UI displays WatchScreen.xaml and any other devices display regular Android UI -> HomePage.xaml.
Xamarin.Forms (Base project) - WatchScreen.xaml.cs
Send message from Wearable device to Android smartphone.
private void btnSendMessage_Clicked(object sender, EventArgs e)
{
MessagingCenter.Send(Xamarin.Forms.Application.Current, MessageKeys.Smartwatch);
}
Xamarin.Forms (Base project) - HomePage.xaml.cs
public HomePage()
{
InitializeComponent();
MessagingCenter.Subscribe<Xamarin.Forms.Application>(Xamarin.Forms.Application.Current, MessageKeys.Smartphone, (sender) =>
{
DisplayAlert("Message", "Wearable message received!", "OK");
});
}
Xamarin.Forms (Native Android Project) - MainActivity.cs
Within MainActivity.cs I implement the following interfaces:
public class MainActivity : WearableActivity, DataClient.IOnDataChangedListener,
GoogleApiClient.IConnectionCallbacks, GoogleApiClient.IOnConnectionFailedListener
Variables:
private GoogleApiClient client;
const string syncPath = "/[project name]/[subdirectory for watch]";
Internal class 'MessageReceiver' for receiving broadcast messages:
[BroadcastReceiver]
public class MessageReciever : BroadcastReceiver
{
MainActivity main;
public MessageReciever() { }
public MessageReciever(MainActivity owner) { this.main = owner; }
public override void OnReceive(Context context, Intent intent)
{
main.ProcessMessage(intent);
}
}
Registering receiver (to receive through Wearable Data Layer API), creating Google Client and Subscribing to smartwatch message (to retrieve message through MessagingCenter)
protected override void OnCreate(Bundle bundle)
{
IntentFilter filter = new IntentFilter(Intent.ActionSend);
MessageReciever receiver = new MessageReciever(this);
LocalBroadcastManager.GetInstance(this).RegisterReceiver(receiver, filter);
client = new GoogleApiClient.Builder(this, this, this)
.AddApi(WearableClass.Api)
.Build();
MessagingCenter.Subscribe<Xamarin.Forms.Application>(Xamarin.Forms.Application.Current, MessageKeys.Smartwatch, (sender) =>
{
SendData();
});
}
ProcessMessage method: sends received message from wearable to smartphone
public void ProcessMessage(Intent intent)
{
// For now I'm not sending the payload...
string message = intent.GetStringExtra("WearMessage");
MessagingCenter.Send(Xamarin.Forms.Application.Current, MessageKeys.Smartphone);
}
SendData(), OnStart(), OnStop(), OnDataChanged (didn't do anything with this part, because this is to receive messages outside the project and I don't need it for now), OnConnected(), OnConnectionSuspended(), OnConnectionFailed():
See the reference to see what code has been used, since code is exactly the same... P.S.: one thing for SendData has been changed. If you want to keep sending data, remove 'client.Disconenct()' from finally after the try and catch block.
Xamarin.Forms (Native Android Project) - WearableService inherits from WearableListenerService:
WearableService is a new class and created within the native project. Also for this part see the reference, because it's the exact same code being used within my project.
To get an overall overview of what's happening, I've visualized this in the diagram below: (example shows how communication works from smartwatch to smartphone)
If you want to communicate from smartphone to smartwatch, you could do something like this:
That's it guys. Now you will receive messages within the same application using the Wearable Data Layer API and MessagingCenter. Instead of having separate projects, we just use separate UIs to make this happen...

Visual Basic Form stops processes half way through [duplicate]

When I create a new project, I get a strange behavior for unhandled exceptions. This is how I can reproduce the problem:
1) create a new Windows Forms Application (C#, .NET Framework 4, VS2010)
2) add the following code to the Form1_Load handler:
int vara = 5, varb = 0;
int varc = vara / varb;
int vard = 7;
I would expect that VS breaks and shows an unhandled exception message at the second line. However, what happens is that the third line is just skipped without any message and the application keeps running.
I don't have this problem with my existing C# projects. So I guess that my new projects are created with some strange default settings.
Does anyone have an idea what's wrong with my project???
I tried checking the boxes in Debug->Exceptions. But then executions breaks even if I handle the exception in a try-catch block; which is also not what I want. If I remember correctly, there was a column called "unhandled exceptions" or something like this in this dialog box, which would do excatly what I want. But in my projects there is only one column ("Thrown").
This is a nasty problem induced by the wow64 emulation layer that allows 32-bit code to run on the 64-bit version of Windows 7. It swallows exceptions in the code that runs in response to a notification generated by the 64-bit window manager, like the Load event. Preventing the debugger from seeing it and stepping in. This problem is hard to fix, the Windows and DevDiv groups at Microsoft are pointing fingers back and forth. DevDiv can't do anything about it, Windows thinks it is the correct and documented behavior, mysterious as that sounds.
It is certainly documented but just about nobody understands the consequences or thinks it is reasonable behavior. Especially not when the window procedure is hidden from view of course, like it is in any project that uses wrapper classes to hide the window plumbing. Like any Winforms, WPF or MFC app. Underlying issue is Microsoft could not figure out how to flow exceptions from 32-bit code back to the 64-bit code that triggered the notification back to 32-bit code that tries to handle or debug the exception.
It is only a problem with a debugger attached, your code will bomb as usual without one.
Project > Properties > Build tab > Platform target = AnyCPU and untick Prefer 32-bit. Your app will now run as a 64-bit process, eliminating the wow64 failure mode. Some consequences, it disables Edit + Continue for VS versions prior to VS2013 and might not always be possible when you have a dependency on 32-bit code.
Other possible workarounds:
Debug > Exceptions > tick the Thrown box for CLR exceptions to force the debugger to stop at the line of code that throws the exception.
Write try/catch in the Load event handler and failfast in the catch block.
Use Application.SetUnhandledExceptionMode(UnhandledExceptionMode.CatchException) in the Main() method so that the exception trap in the message loop isn't disabled in debug mode. This however makes all unhandled exceptions hard to debug, the ThreadException event is pretty useless.
Consider if your code really belongs in the Load event handler. It is very rare to need it, it is however very popular in VB.NET and a swan song because it is the default event and a double-click trivially adds the event handler. You only ever really need Load when you are interested in the actual window size after user preferences and autoscaling is applied. Everything else belongs in the constructor.
Update to Windows 8 or later, they have this wow64 problem solved.
In my experience, I only see this issue when I'm running with a debugger attached. The application behaves the same when run standalone: the exception is not swallowed.
With the introduction of KB976038, you can make this work as you'd expect again. I never installed the hotfix, so I'm assuming it came as part of Win7 SP1.
This was mentioned in this post:
The case of the disappearing OnLoad exception – user-mode callback exceptions in x64
Here's some code that will enable the hotfix:
public static class Kernel32
{
public const uint PROCESS_CALLBACK_FILTER_ENABLED = 0x1;
[DllImport("Kernel32.dll")]
public static extern bool SetProcessUserModeExceptionPolicy(UInt32 dwFlags);
[DllImport("Kernel32.dll")]
public static extern bool GetProcessUserModeExceptionPolicy(out UInt32 lpFlags);
public static void DisableUMCallbackFilter() {
uint flags;
GetProcessUserModeExceptionPolicy(out flags);
flags &= ~PROCESS_CALLBACK_FILTER_ENABLED;
SetProcessUserModeExceptionPolicy(flags);
}
}
Call it at the beginning of your application:
[STAThread]
static void Main()
{
Kernel32.DisableUMCallbackFilter();
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new Form1());
}
I've confirmed (with the the simple example shown below) that this works, just as you'd expect.
protected override void OnLoad(EventArgs e) {
throw new Exception("BOOM"); // This will now get caught.
}
So, what I don't understand, is why it was previously impossible for the debugger to handle crossing kernel-mode stack frames, but with this hotfix, they somehow figured it out.
As Hans mentions, compile the application and run the exe without a debugger attached.
For me the problem was changing a Class property name that a BindingSource control was bound to. Running without the IDE I was able to see the error:
Cannot bind to the property or column SendWithoutProofReading on the
DataSource. Parameter name: dataMember
Fixing the BindingSource control to bind to the updated property name resolved the problem:
I'm using WPF and ran into this same problem. I had tried Hans 1-3 suggestions already, but didn't like them because studio wouldn't stop at where the error was (so I couldn't view my variables and see what was the problem).
So I tried Hans' 4th suggestion. I was suprised at how much of my code could be moved to the MainWindow constructor without any issue. Not sure why I got in the habit of putting so much logic in the Load event, but apparently much of it can be done in the ctor.
However, this had the same problem as 1-3. Errors that occur during the ctor for WPF get wrapped into a generic Xaml exception. (an inner exception has the real error, but again I wanted studio to just break at the actual trouble spot).
What ended up working for me was to create a thread, sleep 50ms, dispatch back to main thread and do what I need...
void Window_Loaded(object sender, RoutedEventArgs e)
{
new Thread(() =>
{
Thread.Sleep(50);
CrossThread(() => { OnWindowLoaded(); });
}).Start();
}
void CrossThread(Action a)
{
this.Dispatcher.BeginInvoke(a);
}
void OnWindowLoaded()
{
...do my thing...
This way studio would break right where an uncaught exception occurs.
A simple work-around could be if you can move your init code to another event like as Form_Shown which called later than Form_Load, and use a flag to run startup code at first form shown:
bool firstLoad = true; //flag to detect first form_shown
private void Form1_Load(object sender, EventArgs e)
{
//firstLoad = true;
//dowork(); //not execute initialization code here (postpone it to form_shown)
}
private void Form1_Shown(object sender, EventArgs e)
{
if (firstLoad) //simulate Form-Load
{
firstLoad = false;
dowork();
}
}
void dowork()
{
var f = File.OpenRead(#"D:\NoSuchFile756.123"); //this cause an exception!
}

VB.NET System.IndexOutOfRangeException in checkbox [duplicate]

When I create a new project, I get a strange behavior for unhandled exceptions. This is how I can reproduce the problem:
1) create a new Windows Forms Application (C#, .NET Framework 4, VS2010)
2) add the following code to the Form1_Load handler:
int vara = 5, varb = 0;
int varc = vara / varb;
int vard = 7;
I would expect that VS breaks and shows an unhandled exception message at the second line. However, what happens is that the third line is just skipped without any message and the application keeps running.
I don't have this problem with my existing C# projects. So I guess that my new projects are created with some strange default settings.
Does anyone have an idea what's wrong with my project???
I tried checking the boxes in Debug->Exceptions. But then executions breaks even if I handle the exception in a try-catch block; which is also not what I want. If I remember correctly, there was a column called "unhandled exceptions" or something like this in this dialog box, which would do excatly what I want. But in my projects there is only one column ("Thrown").
This is a nasty problem induced by the wow64 emulation layer that allows 32-bit code to run on the 64-bit version of Windows 7. It swallows exceptions in the code that runs in response to a notification generated by the 64-bit window manager, like the Load event. Preventing the debugger from seeing it and stepping in. This problem is hard to fix, the Windows and DevDiv groups at Microsoft are pointing fingers back and forth. DevDiv can't do anything about it, Windows thinks it is the correct and documented behavior, mysterious as that sounds.
It is certainly documented but just about nobody understands the consequences or thinks it is reasonable behavior. Especially not when the window procedure is hidden from view of course, like it is in any project that uses wrapper classes to hide the window plumbing. Like any Winforms, WPF or MFC app. Underlying issue is Microsoft could not figure out how to flow exceptions from 32-bit code back to the 64-bit code that triggered the notification back to 32-bit code that tries to handle or debug the exception.
It is only a problem with a debugger attached, your code will bomb as usual without one.
Project > Properties > Build tab > Platform target = AnyCPU and untick Prefer 32-bit. Your app will now run as a 64-bit process, eliminating the wow64 failure mode. Some consequences, it disables Edit + Continue for VS versions prior to VS2013 and might not always be possible when you have a dependency on 32-bit code.
Other possible workarounds:
Debug > Exceptions > tick the Thrown box for CLR exceptions to force the debugger to stop at the line of code that throws the exception.
Write try/catch in the Load event handler and failfast in the catch block.
Use Application.SetUnhandledExceptionMode(UnhandledExceptionMode.CatchException) in the Main() method so that the exception trap in the message loop isn't disabled in debug mode. This however makes all unhandled exceptions hard to debug, the ThreadException event is pretty useless.
Consider if your code really belongs in the Load event handler. It is very rare to need it, it is however very popular in VB.NET and a swan song because it is the default event and a double-click trivially adds the event handler. You only ever really need Load when you are interested in the actual window size after user preferences and autoscaling is applied. Everything else belongs in the constructor.
Update to Windows 8 or later, they have this wow64 problem solved.
In my experience, I only see this issue when I'm running with a debugger attached. The application behaves the same when run standalone: the exception is not swallowed.
With the introduction of KB976038, you can make this work as you'd expect again. I never installed the hotfix, so I'm assuming it came as part of Win7 SP1.
This was mentioned in this post:
The case of the disappearing OnLoad exception – user-mode callback exceptions in x64
Here's some code that will enable the hotfix:
public static class Kernel32
{
public const uint PROCESS_CALLBACK_FILTER_ENABLED = 0x1;
[DllImport("Kernel32.dll")]
public static extern bool SetProcessUserModeExceptionPolicy(UInt32 dwFlags);
[DllImport("Kernel32.dll")]
public static extern bool GetProcessUserModeExceptionPolicy(out UInt32 lpFlags);
public static void DisableUMCallbackFilter() {
uint flags;
GetProcessUserModeExceptionPolicy(out flags);
flags &= ~PROCESS_CALLBACK_FILTER_ENABLED;
SetProcessUserModeExceptionPolicy(flags);
}
}
Call it at the beginning of your application:
[STAThread]
static void Main()
{
Kernel32.DisableUMCallbackFilter();
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new Form1());
}
I've confirmed (with the the simple example shown below) that this works, just as you'd expect.
protected override void OnLoad(EventArgs e) {
throw new Exception("BOOM"); // This will now get caught.
}
So, what I don't understand, is why it was previously impossible for the debugger to handle crossing kernel-mode stack frames, but with this hotfix, they somehow figured it out.
As Hans mentions, compile the application and run the exe without a debugger attached.
For me the problem was changing a Class property name that a BindingSource control was bound to. Running without the IDE I was able to see the error:
Cannot bind to the property or column SendWithoutProofReading on the
DataSource. Parameter name: dataMember
Fixing the BindingSource control to bind to the updated property name resolved the problem:
I'm using WPF and ran into this same problem. I had tried Hans 1-3 suggestions already, but didn't like them because studio wouldn't stop at where the error was (so I couldn't view my variables and see what was the problem).
So I tried Hans' 4th suggestion. I was suprised at how much of my code could be moved to the MainWindow constructor without any issue. Not sure why I got in the habit of putting so much logic in the Load event, but apparently much of it can be done in the ctor.
However, this had the same problem as 1-3. Errors that occur during the ctor for WPF get wrapped into a generic Xaml exception. (an inner exception has the real error, but again I wanted studio to just break at the actual trouble spot).
What ended up working for me was to create a thread, sleep 50ms, dispatch back to main thread and do what I need...
void Window_Loaded(object sender, RoutedEventArgs e)
{
new Thread(() =>
{
Thread.Sleep(50);
CrossThread(() => { OnWindowLoaded(); });
}).Start();
}
void CrossThread(Action a)
{
this.Dispatcher.BeginInvoke(a);
}
void OnWindowLoaded()
{
...do my thing...
This way studio would break right where an uncaught exception occurs.
A simple work-around could be if you can move your init code to another event like as Form_Shown which called later than Form_Load, and use a flag to run startup code at first form shown:
bool firstLoad = true; //flag to detect first form_shown
private void Form1_Load(object sender, EventArgs e)
{
//firstLoad = true;
//dowork(); //not execute initialization code here (postpone it to form_shown)
}
private void Form1_Shown(object sender, EventArgs e)
{
if (firstLoad) //simulate Form-Load
{
firstLoad = false;
dowork();
}
}
void dowork()
{
var f = File.OpenRead(#"D:\NoSuchFile756.123"); //this cause an exception!
}

Windows Phone - developing a caller ID app

I'm not a Windows Phone developer myself, so I apologize in advance for my lack of knowledge.
One of the products we offer our customers is a caller ID app. The software does the following:
Detect incoming calls and get the caller number
If the number isn't found in contacts, do a name search on our server (HTTP Get request to an XML interface)
If a name is found from our server, display it on screen while the phone is ringing
(Other stuff, such as storing results to contacts etc.)
We've implemented the app on Android and Symbian and it works perfectly. I'd like to know if this type of application is even possible on a Windows Phone. According to our subcontractor, this hasn't been the case with previous versions. I'd like to know if this is really true and if things have changed in WP8.
My questions:
Can an application be run as a background process?
Do incoming calls fire events that can be detected by the background process?
Can you get the caller phone number from an incoming call in real time?
Can you perform the search in the background during an incoming call?
Can you display anything on the screen during an incoming call?
From what I've googled, I've only found mentions about the "Obscured" event, nothing about a "Call" event or similar. This isn't very promising, but I'd like to hear from actual developers.
Yes (look up "Background Agents," http://www.jeffblankenburg.com/2011/11/25/31-days-of-mango-day-25-background-agents/).
You should start there and then perform more independent research related to the spec of your app.
Per Jeff's article:
Launch Visual Studio and create a new project. Under Silverlight for Windows Phone, select Windows Phone Application. Name it “MyAgentApp”.
You’ve now created the main application. It will be responsible for two things:
1) Having a live tile that the Background Agent can update with information
2) Starting and stopping the Background Agent
The Background Agent itself must live in its own special project. Add a new project to your solution, selecting Windows Phone Scheduled Task Agent. Name it MyAgent. This project will contain your custom code that will run in the background and update the live tile.
Finally, and this is important, go to the MyAgentApp project and add a project reference to MyAgent. This will allow you to register your agent from within the application. Also, notice the entry this automatically created in WMAppManifest.xml:
<Tasks>
<DefaultTask Name="_default" NavigationPage="MainPage.xaml" />
<ExtendedTask Name="BackgroundTask">
<BackgroundServiceAgent Specifier="ScheduledTaskAgent" Name="MyAgent" Source="MyAgent" Type="MyAgent.ScheduledAgent" />
</ExtendedTask>
</Tasks>
Now it’s time to actually wire everything up. Open MainPage.xaml and add two buttons, one for starting the agent, and the other for stopping the agent:
<StackPanel VerticalAlignment="Center">
<Button Content="Start Background Agent"
Click="StartButton_Click"/>
<Button Content="Stop Background Agent"
Click="StopButton_Click"/>
</StackPanel>
In MainPage.xaml.cs, wire up the buttons to start and stop the agent:
private const string TASK_NAME = "MyAgent";
private void StartButton_Click(object sender, RoutedEventArgs e)
{
StartAgent();
}
private void StopButton_Click(object sender, RoutedEventArgs e)
{
StopAgentIfStarted();
}
private void StartAgent()
{
StopAgentIfStarted();
PeriodicTask task = new PeriodicTask(TASK_NAME);
task.Description = "This is our custom agent for Day 25 - Background Agents";
ScheduledActionService.Add(task);
#if DEBUG
// If we're debugging, attempt to start the task immediately
ScheduledActionService.LaunchForTest(TASK_NAME, new TimeSpan(0, 0, 1));
#endif
}
private void StopAgentIfStarted()
{
if (ScheduledActionService.Find(TASK_NAME) != null)
{
ScheduledActionService.Remove(TASK_NAME);
}
}
Notice that to create our custom agent, we are creating a new PeriodicTask. We then use the name as an identifier when finding and stopping the agent. Notice also that we specified PeriodicTask.Description – this is a required field and will appear in Settings | Background Tasks under the name of our application.
In the MyAgent project, open ScheduledAgent.cs and add the following code:
protected override void OnInvoke(ScheduledTask task)
{
UpdateAppTile(GetLastUpdatedTimeMessage());
}
private string GetLastUpdatedTimeMessage()
{
return string.Format("Last Updated: {0}", DateTime.Now);
}
private void UpdateAppTile(string message)
{
ShellTile appTile = ShellTile.ActiveTiles.First();
if (appTile != null)
{
StandardTileData tileData = new StandardTileData
{
BackContent = message
};
appTile.Update(tileData);
}
}
ScheduledAgent has one important method to override – OnInvoke. This is where your agent will execute its background task. If your task is complete and you no longer need your agent to run, you can call NotifyComplete() to signal that the task completed successfully or Abort() to signal that you are cancelling your task. To keep the task running at an interval, simply do not call either, which is what we are doing here.

"Collection was modified; enumeration operation may not execute" error on deployment

I'm getting this error when I deploy a VB.NET application and for the life of me I cannot figure out why.
I do not get this error when I run the app from the IDE and the test machine I am deploying it to has a similar configuration to the dev machine...Windows 7 & .NET 3.51 SP1 and 4.0.
The app bombs out when the main form is loaded after logging in. I've narrowed it down to the main form because if I load another form from login and then open the main form, this happens.
Linked below is a screenshot of the stack trace.
Any ideas? I'm really lost here.
Thanks.
I do not see a way for ShapeCollection.Dispose() to throw that exception. Although it is manipulating a List<> that can indeed throw that exception, the code should not trigger it:
private void Dispose(bool disposing)
{
if (!this.m_Disposed && disposing)
{
for (int i = this.m_Shapes.Count - 1; i >= 0; i--)
{
this.m_Shapes[i].Dispose();
}
this.m_Shapes.Clear();
this.m_Shapes = null;
}
this.m_Disposed = true;
}
Well, this is from the PowerPacks version that I have. There have been a couple of versions of it floating around, it used to be distributed separately. Make sure you didn't accidentally deploy an old version.