C
C#3mo ago
IcyIme

✅ A second operation was started on this context instance before a previous operation completed.

i have two layoust one for mobile and second for pc and when i use mobile layout it throws me this error
System.InvalidOperationException: A second operation was started on this context instance before a previous operation completed. This is usually caused by different threads concurrently using the same instance of DbContext. For more information on how to avoid threading issues with DbContext, see https://go.microsoft.com/fwlink/?linkid=2097913.
at Microsoft.EntityFrameworkCore.Infrastructure.Internal.ConcurrencyDetector.EnterCriticalSection()
at Microsoft.EntityFrameworkCore.Query.Internal.SingleQueryingEnumerable`1.Enumerator.MoveNext()
at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
at GradeProject.Components.Pages.ProfilePage.GetLeaderboardPositionAsync(Int32 score) in c:\Users\peter\Desktop\Grade\GradeProject\GradeProject\Components\Pages\ProfilePage.razor:line 143
at GradeProject.Components.Pages.ProfilePage.OnInitializedAsync() in c:\Users\peter\Desktop\Grade\GradeProject\GradeProject\Components\Pages\ProfilePage.razor:line 135
at Microsoft.AspNetCore.Components.ComponentBase.RunInitAndSetParametersAsync()

System.InvalidOperationException: A second operation was started on this context instance before a previous operation completed. This is usually caused by different threads concurrently using the same instance of DbContext. For more information on how to avoid threading issues with DbContext, see https://go.microsoft.com/fwlink/?linkid=2097913.
at Microsoft.EntityFrameworkCore.Infrastructure.Internal.ConcurrencyDetector.EnterCriticalSection()
at Microsoft.EntityFrameworkCore.Query.Internal.SingleQueryingEnumerable`1.Enumerator.MoveNext()
at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
at GradeProject.Components.Pages.ProfilePage.GetLeaderboardPositionAsync(Int32 score) in c:\Users\peter\Desktop\Grade\GradeProject\GradeProject\Components\Pages\ProfilePage.razor:line 143
at GradeProject.Components.Pages.ProfilePage.OnInitializedAsync() in c:\Users\peter\Desktop\Grade\GradeProject\GradeProject\Components\Pages\ProfilePage.razor:line 135
at Microsoft.AspNetCore.Components.ComponentBase.RunInitAndSetParametersAsync()

csharp @using GradeProject.Components.Account.Shared

<MediaQueryList>
<ViewTransitionRouter AppAssembly="typeof(Program).Assembly">
<Found Context="routeData">
<AuthorizeRouteView RouteData="routeData" DefaultLayout="@(isMobile ? typeof(Layout.MobileLayout) : typeof(Layout.MainLayout))">
<NotAuthorized>
<RedirectToLogin/>
</NotAuthorized>
</AuthorizeRouteView>
<FocusOnNavigate RouteData="routeData" Selector="[autofocus]"/>
</Found>
</ViewTransitionRouter>
<MediaQuery Media="(max-width: 600px)" @bind-Matches="isMobile" />
</MediaQueryList>

@code {
private bool isMobile;
}
csharp @using GradeProject.Components.Account.Shared

<MediaQueryList>
<ViewTransitionRouter AppAssembly="typeof(Program).Assembly">
<Found Context="routeData">
<AuthorizeRouteView RouteData="routeData" DefaultLayout="@(isMobile ? typeof(Layout.MobileLayout) : typeof(Layout.MainLayout))">
<NotAuthorized>
<RedirectToLogin/>
</NotAuthorized>
</AuthorizeRouteView>
<FocusOnNavigate RouteData="routeData" Selector="[autofocus]"/>
</Found>
</ViewTransitionRouter>
<MediaQuery Media="(max-width: 600px)" @bind-Matches="isMobile" />
</MediaQueryList>

@code {
private bool isMobile;
}
3 Replies
exixt
exixt3mo ago
how does GetLeaderBoardPositionAsync look like
Jimmacle
Jimmacle3mo ago
an instance of a EF Core dbcontext cannot be used concurrently, the error is pretty much telling you what's wrong if you're using EF directly in blazor components you should consider injecting IDbContextFactory<YourDbContext> instead of the dbcontext itself because blazor component lifetimes don't match the lifetime you should have for dbcontexts
IcyIme
IcyIme3mo ago
thanks
Want results from more Discord servers?
Add your server