Hey, thanks, I really appreciate you responding. Our use case is this: we use a 3rd-party web app (Autodesk Flow Production Tracking) that uses a custom URL scheme to launch a desktop app (RV). This works fine. However, it is not uncommon for more than one version of the desktop app to be installed on any given machine for various reasons (feature requirements for different different projects, testing, troubleshooting). In addition, the desktop app supports site-customized scripted "add-ons" that require context-dependent environment variables to work properly. So historically, we have used LSSetDefaultHandlerForURLScheme to point the custom URL scheme to an in-house app that did the environment setup work and then launched the required version of the desktop app. Now, we are finding it hard to keep the custom URL scheme reliably pointed to our environment setup app. Since it registers the same custom URL scheme as the Autodesk desktop app, what actually gets launched is now by definition undefined. This ends up being very confusing and frustrating for our users.