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13 results for “async”

The .NET Developer Interview · Part 3

async/await Interview Questions (the Deadlock Special)

Never fumble an async question again. Why async void is dangerous, how .Result deadlocks, Task vs Thread and cancellation, with traps you reproduce yourself. Aug 7, 2026 7 min read

C#: 'CS4033 The await operator can only be used within an async method'

CS4033 means await sits in a method not marked async. Add async, return Task instead of void and await the call; why not async void is inside. Nov 6, 2026 2 min read

ASP.NET Core: 'Synchronous operations are disallowed. Call ReadAsync ...' (AllowSynchronousIO)

ReadToEnd on Request.Body is a blocking read Kestrel refuses. Await ReadToEndAsync instead; why AllowSynchronousIO is only an escape hatch is inside. Oct 23, 2026 2 min read

Blazor: 'The current thread is not associated with the Dispatcher. Use InvokeAsync()'

A timer called StateHasChanged off the Blazor Dispatcher. Wrap the update in InvokeAsync; left alone, it crashed the whole server process. Sep 25, 2026 2 min read

async/await Explained with a Coffee Shop

Why does your app freeze? Because someone is waiting where they should be brewing. Asynchronous code explained with baristas, plus C# examples. Jul 30, 2026 5 min read

MAUI SecureStorage.GetAsync throws on Android after a keystore reset

A value that saved fine yesterday throws on read today. Android's keystore invalidated the key and SecureStorage cannot decrypt. Treat the value as gone. Sep 4, 2026 2 min read

HttpClient GetFromJsonAsync: '<' is an invalid start of a value (the server sent HTML, not JSON)

The server answered with an HTML page instead of JSON. How to see what came back and check status and Content-Type first is inside. Oct 30, 2026 2 min read

Blazor: Beginner to Intermediate · Part 11

Calling Web APIs from Blazor with HttpClient

Fetch live data with HttpClient and GetFromJsonAsync. Handle loading and errors gracefully, and display API results in your UI. Jul 30, 2026 6 min read

MAUI Android: 'No maps app' or ActivityNotFoundException with Google Maps installed

Google Maps is installed, yet your app says no maps app. TryOpenAsync returns false because Android 11's package visibility rules need a queries block. Sep 4, 2026 2 min read

C#: 'CS0029 Cannot implicitly convert type Task<int> to int' (missing await)

CS0029 with Task<int> means an async call lacks await. The method returns a task, not the number; the one-word fix and why .Result is risky are inside. Nov 6, 2026 2 min read

C#: 'CS4014 Because this call is not awaited, execution of the current method continues'

CS4014 is a warning that an async call runs unawaited. In the test the order file was never written; the one-word fix is inside. Nov 6, 2026 2 min read

Ollama from .NET: 'JsonException: '{' is invalid after a single JSON value'

ReadFromJsonAsync fails because Ollama streams by default. Each line is its own JSON object; stream false and a line reader are inside, tested. Nov 6, 2026 2 min read

Blazor: 'JavaScript interop calls cannot be issued at this time' during prerendering

JavaScript is not reachable while Blazor prerenders a component. Move the call to OnAfterRenderAsync(firstRender), or turn prerendering off. Sep 25, 2026 2 min read