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Hot Reload vs. Edit and Continue: Choosing a Debug Iteration Strategy for .NET 8 Apps
Sky Byte
0 reputation · 15 Jun 2024, 05:32 UTC
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0 reputation · 15 Jun 2024, 05:32 UTC
Visual Studio 2022 offers two mechanisms for applying code changes during a debug session without restarting: Hot Reload (introduced in 2022) and the legacy Edit and Continue (EnC). Hot Reload applies edits while the process continues running, supporting a wider range of changes such as adding methods, modifying lambdas, and updating Razor components. Edit and Continue requires the debugger to be paused at a breakpoint and does not support asynchronous methods, generic type modifications, or iterator blocks.
The primary constraint is minimizing developer iteration time for a .NET 8 application that includes both backend services and a Blazor Server front end. Hot Reload is faster for UI-heavy flows because it never forces a pause, but it can fail silently for unsupported edits—particularly those involving generic type parameters or async state machines—leaving the running code unchanged without a clear error in the Output window.
When Hot Reload encounters an unsupported edit, Visual Studio may silently fall back to Edit and Continue if the debugger is already paused. The exact conditions that trigger this fallback are not fully documented and appear to vary by .NET runtime version. This makes it difficult to predict whether a given edit will be applied seamlessly, require a manual pause, or demand a full restart.
35275 reputation · 15 Jun 2024, 07:31 UTC
Hot Reload applies code changes while the process continues running; it falls back to Edit and Continue only when the debugger is already paused, otherwise it requires a full restart. Silent failures are not reliably detected without checking the Hot Reload tool window or Output window. For a mixed Blazor Server and API solution the fallback behavior is the same for both paths.
The IDE falls back to Edit and Continue solely based on the debugger pause state; there is no published list of edit types that trigger fallback.
Changes to generic type parameters, method signatures, or async state machines may cause Hot Reload to fail silently; if the debugger is not paused the IDE will prompt for a restart rather than silently applying Edit and Continue. This depends on the Visual Studio 2022 update level, .NET 8 runtime version, and project type (backend API vs Blazor Server).
To know definitively whether a silent failure will lead to a restart prompt you need the exact Visual Studio 2022 update version and the .NET 8 runtime version you are using.
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