If a project is opened in the Editor after previously having a hot reload performed, any subsequent hot reloads started from Visual Studio will result in the build being reported as failed in Visual Studio even though the Editor reports the hot reload was successful.

When comparing hot reload files in Intermediate\Build\Win64\UE4Editor\Development and Binaries\Win64, the most recent hot reload files in the latter folder have corresponding files in the former folder with the same numerical value in the file name. However, these files do not match the numerical value in the name of the file that Visual Studio reports as having been unable to produce.

Yes. This behavior did not occur in 4.14. Attempting to open a project that had previously had a hot reload would result in a prompt appearing saying the project .dll file could not be found and asking if it should be built.

Steps to Reproduce
  1. Create a new Third Person code project.
  2. Open the project in the Editor, and the solution in Visual Studio.
  3. Add or remove a blank line from a source file in Visual Studio.
  4. Build the project in Visual Studio to trigger a hot reload in the Editor.
  5. Once the hot reload completes successfully, close the Editor.
  6. Open the project in the Editor again.
  7. Add or remove another blank line in a source file in Visual Studio.
  8. Build the project in Visual Studio to trigger a hot reload in the Editor.

Visual Studio reports that the build failed, displaying a message similar to ERROR : UBT error : Failed to produce item: D:\Unreal Projects\Current Issues\tps16\Intermediate\Build\Win64\UE4Editor\Development\UE4Editor-tps16-7257.lib. However, the Editor shows that the hot reload was successful.

The build completes successfully in Visual Studio.

Delete the project's Intermediates folder, generate project files, and build the project normally in Visual Studio.

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ComponentUE - Foundation - Cpp Tools - Hot Reload
Affects Versions4.
Target Fix4.16.2
Fix Commit3475747
CreatedFeb 21, 2017
ResolvedJun 6, 2017
UpdatedApr 27, 2018
Pull Requests
4447 - klorberg