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Fixed in 2021.3.18f1, 2022.2.5f1, 2023.1.0a26



Found in






Issue ID




Switching between debug and release mode multiple times is not handled correctly



Reproduction steps:
# Open the user’s attached project
# Open the “SampleScene” Scene
# Open file Test.cs in Visual Studio
# Put a breakpoint in the method OnValidate
# Hit F5 to start the debugger, and wait for debugging session to start
# Unity asks for enabling debugging, click "Enable debugging for this session"
# Hit F5 to continue
# Back in Unity, edit member "Value" of object Test to trigger again the debug breakpoint
# Close the debugging session in Visual Studio ( Shift F5 )
# Back in Unity, click the debug icon in the lower right corner of the Main Window, which pops up a dialog about debugging
# Click on "Switch to release mode"
# Try to start debugging session directly from Visual Studio (F5)

Expected result: Debugging session starts
Actual result: Debugging session does not start

Reproducible with: 2020.3.40f1, 2021.3.11f1 2022.1.19f1. 2022.2.0b9, 2023.1.0a13

Reproduced on: Windows 10 Pro 21H2, 

* In Visual Studio, click on "Debug/Attach Unity Debugger", and notice that now we have 3 different debugger instances displayed
* Note that this is not related to Visual Studio 2022, the same issue reproduces with Visual Studio 2019
* If reload assemblies never load, delete the projects library and try again

  1. Resolution Note (fix version 2023.1.0a26):

    Fixed issue where the Unity runtime would refuse C# debugger connections after alternating between release & debug optimizations multiple times.

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