Xamarin form preview shows only Mockview - visual-studio-2019

I am using Xamarin Forms on Visual Studio 2019. In every XAML forms of my project, when I try to show the preview I get only an orange box with the text "Mockview". I don't get any error message. My application build and works corretly but I can't see the preview.
This is the screenshot:
My exact versions are:
Microsoft Visual Studio Enterprise 2019 Version 16.2.3
Microsoft .NET Framework Version 4.8.03752
Xamarin 16.2.0.95
Xamarin Designer 16.2.0.375
Xamarin Templates 16.3.117
Xamarin.Android SDK 9.4.1.0
Any suggestion?
UPDATE:
The problem appears in release mode. In debug mode, after full reboot, it works, but sometimes not.
Sometimes appears an error:
System.NullReferenceException: Object reference not set to an instance of an object.
at Xamarin.AndroidDesigner.DesignerProject.set_PreferredTheme(Theme value) in E:\A\_work\89\s\Xamarin.Designer.Android\Xamarin.AndroidDesigner\DesignerProject.cs:line 858
at Xamarin.AndroidDesigner.AndroidDesignerSession.SetTheme(Theme theme, Boolean triggerChange) in E:\A\_work\89\s\Xamarin.Designer.Android\Xamarin.AndroidDesigner\AndroidDesignerSession.cs:line 370
at Xamarin.Designer.Forms.Preview.AndroidXamlRenderer.<RenderOneXaml>d__23.MoveNext() in E:\A\_work\89\s\Xamarin.Designer.Forms\Xamarin.Designer.Forms.Preview\Android\AndroidXamlRenderer.cs:line 151
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd(Task task)
at Xamarin.Designer.Forms.Preview.AndroidXamlRenderer.<RenderXamls>d__24.MoveNext() in E:\A\_work\89\s\Xamarin.Designer.Forms\Xamarin.Designer.Forms.Preview\Android\AndroidXamlRenderer.cs:line 286
--- End of stack trace from previous location where exception was thrown ---
at Microsoft.VisualStudio.Telemetry.WindowsErrorReporting.WatsonReport.GetClrWatsonExceptionInfo(Exception exceptionObject)
Sometimes appears the error:

It's based on your design, when you design perfectly, it will work but anyone attribute will not valid or wrong, it doesn't shown but the output comes perfectly. because not valid attributes are ignored.
I recommend to use HotXaml or Live Reload

Related

An error appeared when opening TDS Solution: 'The operation has timed out' occurred while checking for your license

I'm trying to load a TDS solution from the Clothing Company Sample Solution provided in learning#sitecore but when I tried to load it, a few error messages appeared. First one is Sitecore TDS license cant be verified.
The second error appears when I reload the TDS project. Project Unsupported error.
Things I have tried:
Reinstall TDS
Restart Visual Studio and PC
Repair Visual Studio
The output from Visual Studio:
The error 'The operation has timed out' occured while checking your license.
This error occurs when Visual Studio is blocked from accessing the Sitecore license server.
Please contact developersupport#sitecore.com for more information on resolving this error.
Exception The operation has timed out (WebException):
at System.Net.HttpWebRequest.GetRequestStream(TransportContext& context)
at System.Net.HttpWebRequest.GetRequestStream()
at System.Web.Services.Protocols.SoapHttpClientProtocol.Invoke(String methodName, Object[] parameters)
at Hedgehog.LicensingV3.Client.ProductInfo.ProductInfo.ValidateLicense(Byte[] profileBytes)
at Hedgehog.LicensingV3.Client.LicenseValidator.GetActivatedLicense(WorkstationProfile profile, Int32 serviceTimeoutSeconds, Boolean isMultiLicense)
at Hedgehog.LicensingV3.Client.LicenseValidator.ActivateLicense(ILicenseInfoStore licenseInfoStore, Int32 serviceTimeoutSeconds, Boolean contactServer)
at HedgehogDevelopment.SitecoreProject.VSIP.Licensing.TDSLicenseSupport.DownloadNewActivationKey(ILicenseKeyProvider licenseKeyProvider, ILicenseFailureLogger logger, Int32 serviceTimeoutSeconds, Boolean backgroundCheck)
The error 'The operation has timed out' occurred while checking your license.
Just putting this out here. Found the fix. Just have to launch visual studio without selecting any recent projects. Once the visual studio is launched, click on Continue without code and everything should be working fine.

Stop on exception Delphi 10.1

I have recently moved from Delphi 7 to 10.1 Berlin.
I am used to being shown the line where an exception is raised in Delphi7 but the new IDE doesn't seem to work the same. I am just getting the exception notification followed by termination of my application when I close the exception box.
I have searched the options for a 'Stop on exception' checkbox (like Delphi 7) but cannot find it.
This is a fire monkey application by the way
Peter
If you are referring to the option called Stop on Delphi Exceptions within Delphi 7, its current equivalent is called Notify on Language Exceptions and is located via Tools > Options > Debugger Options > Embarcadero Debuggers > Language Exceptions.
Futhermore, I found this related question.

visual studio 2013 ultimate crashing when writing to controller

I have visual studio 2013 ultimate with update 4.
when ever i'm writing in mvc project in the controller VS. is restarting .
I have tried to repair , I tried to uninstall and install again .
I have no problem writing class ,view and so on .
I tried in new project, old project, always the same.
but Yuk (in safeMode from my Xml i'm getting this Error .
Construction of frame content failed.
Frame identifier: ST:0:0:{74946827-37a0-11d2-a273-00c04f8ef4ff}
Frame caption: Server Explorer
Exception details:
System.UnauthorizedAccessException: Access is denied. (Exception from HRESULT: 0x80070005 (E_ACCESSDENIED))
at Microsoft.VisualStudio.Shell.Interop.IVsShell5.LoadPackageWithContext(Guid& packageGuid, Int32 reason, Guid& context)
at Microsoft.VisualStudio.Platform.WindowManagement.WindowFrame.GetPackage()
at Microsoft.VisualStudio.Platform.WindowManagement.WindowFrame.ConstructContent()

Firebird: An unhandled exception of type 'System.NotSupportedException' occurred in FirebirdSql.Data.FirebirdClient.dll

I am creating a project windows runtime component(with c#), and I want to use embedded DB so I added Firebird-2.5.2.26540-0_x64_embed and .net component NETProvider-2.5.2-CF. Every time when I am performing any action on FBcommand and FBConnection i am getting error "An unhandled exception of type 'System.NotSupportedException' occurred in FirebirdSql.Data.FirebirdClient.dll"
I can't use terget framework because its WinRT(c#) project...
Note this answer is actually by #cincura.net on the Firebird .NET mailinglist. I am just posting it here for completeness:
The ADO.NET stack is not available in WinRT, hence you cannot use any
database access. The CF version didn't helped either.
See How should a Windows 8 Metro Application connect to a central database? and How might a Windows 8 Metro app handle back end database access? for potential solutions.

How do I trace an intermittent crash that occurs only under the debugger, but is not caught by it?

I have an odd intermittent crash that only occurs under some circumstances that I am having trouble solving, and I'm seeking SO's advice for how to tackle it.
The bug
At apparently random points, Windows shows the "[App] has stopped working" dialog. It is an APPCRASH in ntdll.dll, exception code 4000001f, exception offset 000a2562. Here's where it gets tricky: this only occurs when running the application under the debugger. However, the debugger does not catch this exception, and at the point where Windows shows this dialog, the IDE is not responding. This bug does not occur when running normally, i.e. not within the IDE debugger.
I can't reproduce it outside the debugger, so I can't run the program and attach when it's already crashed. I can't pause execution when Windows shows this dialog, since the IDE isn't responding. I can manually trace through lines of code to see where it occurs. There are several, and where it occurs is apparently random. For a while it occurred when showing a window (or new form), for a while when creating a thread.
Edit: I have tracked it down to the IDE: if I pause on a breakpoint and click the Thread Status tab, the program will crash immediately with the above dialog even though it is, theoretically, paused. In this situation, the IDE remains responsive. This is really weird.
More information
I have just moved my development environment to VMWare Fusion. The bug also occurs running a build from my old (native Windows) computer on my new computer; it did not occur with the same EXE file on that old computer. This makes me wonder if it is related to Fusion or something in my new setup.
I am running:
Windows 7 Pro x64 on WMWare Fusion 3.1.3 on OSX Lion 10.7.1, all fully updated. Fusion is running in "Full screen" mode on one of my screens.
A colleague running Windows 7 natively (not in a VM) does not encounter this issue. Nor did I on my old Vista computer.
Embarcadero RAD Studio 2010, fully updated (I hope; there are about five updates and getting them all in order is tricky.) I have DDevExtensions 2.4.1 installed, and the latest IDE Fix Pack too: uninstalling both these has no effect.
The application is written mostly in C++, with snippets of Delphi. It is 32-bit.
We use EurekaLog, but the exception is not caught by it either. (Normally, an exception would be caught first by the debugger, then by EurekaLog.)
Running a debug build (no EurekaLog, extra debug info etc, debug DCUs set to true) also reproduces it. However, the "Debug DCUs" option on The Delphi Linking page of the C++Builder project settings dialog seems to have no effect - I can't step into the VCL code and find the line that actually triggers the error.
Codeguard (which detects memory access errors, double frees, access in freed memory, buffer overruns, etc) reports nothing.
This has all the hallmarks of a memory corruption. It only appears when you run under a one particular environment, and occurs at a different location each time. Both classic symptoms.
The best way I know to debug this is to download the full FastMM and run with full debugging options enabled.
If that doesn't help then you are reduced to removing parts of code, one by one, until you can isolate the problem.
Another problem I have seen in D2010 is a problem when mixing local class definitions (i.e. class inside class) with generics. The code generated is fine but the debug DCUs are wrong and when stepping through the code the debugger jumps to the wrong file and dies shortly after. You don't seem to have quite the same problem but there are similarities in the IDE deaths.
Finally I would advise you to suspect your own code rather than VMware. It's always tempting to blame something else but in my experience, whenever I have done so, it was always my code in the end!
I hit a quite similar problem. I've also been developing a .dll and when I've set a breakpoint anywhere in my code, Delphi stopped at the source code line and the host-application crashed immediately.
Closing the "Thread Status Window" in debug layout "fixed" the problem.
I'm working on Windows 7 64-bit and Delphi XE3.
4000001F is STATUS_WX86_BREAKPOINT
In other words, it is INT 3, which was not handled by IDE.
Since it is raised in NTDLL - I would guess that this is indication of memory corruption in system heap. Remember, some Windows code would switch to debugger version when running under debugger. That's why you can not reproduce this when application is running as standalone outside of the debugger - because breakpoint is not generated.
You may try FastMM in full debug mode, but I do not think that it will help you. The corruption does not happen in your memory, it happens in system memory. Yes, perhaps memory allocation scheme will be changed - and your corruption will reveal itself in your code/memory... may be. Try use top-down allocations, try use SafeMM...
Another possible approach would be using Application Verifier.
See also:
Windows has generated a breakpoint
C++ error on Ms Visual Studio: "Windows has triggered a breakpoint in javaw.exe"
http://blogs.msdn.com/b/oldnewthing/archive/2012/01/25/10260334.aspx
http://blogs.msdn.com/b/oldnewthing/archive/2013/12/27/10484882.aspx
Check the The projects dsk file and make sure it does not have a reference pointing to the wrong unit. The fix is to open the dsk in an editor and change the file location to the correct location.

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