Debuging Sandbox Solutions

When debugging a normal SharePoint project, like a Visual Web Part, you will attach Visual Studio debugger to the w3wp.exe but when debugging the sandbox solution you need to attach Visual Studio to an another process. For the sandbox solution code you need to attach to SPUCWorkerProcess.exe and this goes also for the sandbox solution proxy arguments class.

For the sandbox solution proxy operation you need to attach to the SPUCWorkerProcessProxy.exe