sql error when using CancellationToken and cancelling it fast multiple times

this is my code (blazor server):

@inject IDbContextFactory<MyContext> cxf
<button type="button" id="btn1" @onclick="btnClick">Load</button>

    private CancellationTokenSource cts;
    private CancellationTokenSource prevCts;

    private async Task btnClick()
    {
        if (prevCts is not null) prevCts.Cancel();
        cts = new CancellationTokenSource();
        prevCts = cts;

        using var cx = cxf.CreateDbContext();

        var res = await cx.Lunches.ToArrayAsync(cts.Token);
        var res1 = await cx.Categories.ToArrayAsync(cts.Token);
        var res2 = await cx.Countries.ToArrayAsync(cts.Token);
    }

to get the error I’m using js to click the button multiple times instantly: $('#btn1').click().click().click() usually 3 clicks is enough to get the error

Error: Microsoft.Data.SqlClient.SqlException (0x80131904): The request failed to run because the batch is aborted, this can be caused by abort signal sent from client, or another request is running in the same session, which makes the session busy.
Operation cancelled by user.
   at Microsoft.Data.SqlClient.SqlCommand.<>c.<ExecuteDbDataReaderAsync>b__208_0(Task`1 result)
   at System.Threading.Tasks.ContinuationResultTaskFromResultTask`2.InnerInvoke()
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
--- End of stack trace from previous location ---
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.Tasks.Task.ExecuteWithThreadLocal(Task& currentTaskSlot, Thread threadPoolThread)
--- End of stack trace from previous location ---
   at Microsoft.EntityFrameworkCore.Storage.RelationalCommand.ExecuteReaderAsync(RelationalCommandParameterObject parameterObject, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Storage.RelationalCommand.ExecuteReaderAsync(RelationalCommandParameterObject parameterObject, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Query.Internal.SingleQueryingEnumerable`1.AsyncEnumerator.InitializeReaderAsync(AsyncEnumerator enumerator, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.SqlServer.Storage.Internal.SqlServerExecutionStrategy.ExecuteAsync[TState,TResult](TState state, Func`4 operation, Func`4 verifySucceeded, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Query.Internal.SingleQueryingEnumerable`1.AsyncEnumerator.MoveNextAsync()
   at Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.ToListAsync[TSource](IQueryable`1 source, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.ToListAsync[TSource](IQueryable`1 source, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.ToArrayAsync[TSource](IQueryable`1 source, CancellationToken cancellationToken)
...
--- End of stack trace from previous location ---

when 3 clicks doesn’t throw the error, with about 15 I can get this error:

 Error: System.InvalidOperationException: Operation cancelled by user.
   at Microsoft.Data.SqlClient.SqlCommand.<>c.<ExecuteDbDataReaderAsync>b__208_0(Task`1 result)
   at System.Threading.Tasks.ContinuationResultTaskFromResultTask`2.InnerInvoke()
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
--- End of stack trace from previous location ---
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.Tasks.Task.ExecuteWithThreadLocal(Task& currentTaskSlot, Thread threadPoolThread)
--- End of stack trace from previous location ---
   at Microsoft.EntityFrameworkCore.Storage.RelationalCommand.ExecuteReaderAsync(RelationalCommandParameterObject parameterObject, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Storage.RelationalCommand.ExecuteReaderAsync(RelationalCommandParameterObject parameterObject, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Query.Internal.SingleQueryingEnumerable`1.AsyncEnumerator.InitializeReaderAsync(AsyncEnumerator enumerator, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.SqlServer.Storage.Internal.SqlServerExecutionStrategy.ExecuteAsync[TState,TResult](TState state, Func`4 operation, Func`4 verifySucceeded, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Query.Internal.SingleQueryingEnumerable`1.AsyncEnumerator.MoveNextAsync()
   at Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.ToListAsync[TSource](IQueryable`1 source, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.ToListAsync[TSource](IQueryable`1 source, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.ToArrayAsync[TSource](IQueryable`1 source, CancellationToken cancellationToken)
...

Note when the error doesn’t occur (with 2 clicks always), I would see (in ExpressProfiler) that for the cancelled clicks only 1 db request is made and the last one makes all the requests.

Include provider and version information

EF Core version: 7 Database provider: (e.g. Microsoft.EntityFrameworkCore.SqlServer) Target framework: (e.g. .NET 7.0) Operating system: IDE: Visual Studio 2022 17.4

[roji]

@omuleanu what exactly is the behavior you find problematic above? When you trigger a cancellation token, the operation to which it was given is supposed to throw an OperationCanceledException - since the operation can’t complete. It’s your responsibility to catch that exception and handle appropriately (possibly exiting the button click handler right away).

Now, SqlClient specifically doesn’t throw OperationCanceledException, but instead throws a SqlException (see https://github.com/dotnet/SqlClient/issues/26); but that doesn’t seem to be what you’re complaining about (I admit the InvalidOperationException is even more problematic).

[roji]

I was thinking if I click on page 2 and while loading I click on 3 meaning I changed my mind about loading 2 and want page 3 now; so to make it a tiny bit more responsive, instead of locking until the result is back, also I was interested to learn how the Cancellation works.

You can certainly do that - swallowing cancellation exceptions and making sure things are sane in the face of concurrent updating - though I’m not sure that makes for an intuitive UI 😃

In any case, am going to go ahead and close this as it seems that everything is working as expected. But feel free to post back here with further questions.