How can I debug a UWP application on startup?

Question

I'm trying to debug a UWP application, and break on startup. However, when I start the application with windbg, the breakpoint didn't work.

After further digging I found the process is started by system service instead of the explorer, e.g

Any ideas on how to debug UWP application and break on startup?

Answer 1

Registry

Typically you would add an entry into the Image File Execution Options registry area, which lets you invoke a debugger as soon as the named exe is launched.

Assuming a 64bit service:

• Key: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\App1.exe
• Value: debugger REG_SZ
• Data: "C:\Program Files (x86)\Windows Kits\10\Debuggers\x64\windbg.exe"

Notice the name of your exe in the Key path, and any specific debugger (and command line parameters) can be specified.

For 32-bit services, add your new entry to the HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\[app.exe] path.

Just remember to delete (or temporarily rename) the registry when done debugging.

DebugBreak

Alternately, you can add a call to DebugBreak at the start of your process. Its worthwhile to add the check for an app-specific registry setting before calling DebugBreak, that way it is easy to turn on and off.