How to discover which app ‘owns’ the mapping between a filename extension and its UTI, and whether you can do anything to fix a conflict.
LaunchServices
Two command tools, lsregister and lsappinfo, are often recommended for dealing with LaunchServices problems. This summarises what they can and cannot do.
How macOS makes the association between file types and apps for the Finder and GUI, using UTIs and their associated data including filename extensions. Why clashes occur, and how they’re resolved.
How to reduce a 5 second log extract with 3,576 entries to just the 498 you’re most interested in, using Notes and Search features in LogUI, and what they tell us about how macOS 26.5.2 launches a known app.
Without the correct filename extension, macOS appears unable to associate files with apps, preview then using QuickLook, or index them for Spotlight. But there’s more to determining file types than extensions, there’s also a little magic involved.
When you double-click a file and expect to see it opened by the app of your choice, but instead it’s opened by the wrong app, or the wrong version of the right app, or maybe macOS refuses to open it at all. How to fix that.
Which problem-solving techniques are still available in macOS Tahoe? While Intel Macs still have a few, Apple silicon Macs don’t have many left.
For the last 10 years, macOS has relied on Uniform Type Identifiers to recognise different types of files, for opening in apps, QuickLook, Spotlight and in other features.
Introduced in Catalina, RunningBoard now monitors the life cycle of apps, and may manage resources such as memory. Here it’s helping to launch an app through LaunchServices.
How PlugInKit gets information about all installed app extensions, nd how it informs the services that use those extensions. Why killing the LaunchServices database may not be a good idea.
The Eclectic Light Company 