Does the plugin support HTML5? You can check by looking in the project file for the list of supported platforms.
That error is result other error which caused failed to produce that file, can you paste whole log?
Trying to get my game to run on HTML5 everything is working fine but i get a error
UnrealBuildTool: ERROR: UBT ERROR: Failed to produce item: C:\Users\Leonardo\Documents\Unreal Projects\Auto Escola\Plugins\MyCustomPlugin\VictoryPlugin\Binaries\HTML5\VictoryBPLibrary-Static.bc
If or anyone could help me would be awesome!