While the details of each of these issues differ, they all have the same root cause: On Windows, Chromium did not launch Native Message Hosts directly, instead launching cmd.exe (Windows’ console command prompt) and directing it to launch the target Host: crbug/387233 – Broken when cmd.exe is disabled or set to RUNASADMIN.crbug/387228 – Broken if %comspec% not pointed at cmd.exe.crbug/335558 – Ampersand in Host’s path prevents launching.

While these bugs are typically only seen in uncommon configurations, they could break Native Messaging entirely for some users. However, over the years, users have reported a trail of bugs related to how the feature is implemented on Windows. Native Messaging is a powerful capability, and a common choice for building extensions that need to interact with the rest of the system.

Previously, I’ve written about Chromium’s Native Messaging functionality that allows a browser extension to talk to a process running outside of the browser’s sandbox, and I shared a Native Messaging Debugger I wrote that allows you to monitor (and even tamper with) the communication channels between the browser extension and the Host App.

Windows process monitoring software