I had what I believe is the same issue and it took me forever to figure out. I believe the full error I got in the console was Error Domain=NSFileProviderErrorDomain Code=-2003 "An older version of the application is currently in use which maps to olderExtensionVersionRunning. https://developer.apple.com/documentation/fileprovider/nsfileprovidererror/code/olderextensionversionrunning It occurs when you run the extension from different file system locations. It is caused by the older version of your extension never being removed from the plugin registry. I have found what fixes it is described in this stackoverflow post: https://stackoverflow.com/questions/44211893/extensions-pluginkit-and-craziness-on-macos In summary: Use pluginkit -v -m -D -i my.bundle.id to get the location of your old extension. Use pluginkit -r path-to-my-extension to remove it. Extra tip: you can use pluginkit -vvvvm to list all your registered plugins. Hope that helps :)

Upon further inspection I found that I'm getting an error in the Console that seems to be the cause of the issue: "Sandbox: fileproviderd(684) deny(1) file-read-data /Applications/myApp.app/Contents/PlugIns/myHelperApp.app". Any clues as to how to resolve this issue? Is this is a code signing issue? If so I am failing to see what I am doing wrong. I am signing my helper app through XCode with a MacOS provisioning profile, packaging it within my application, and then signing my application.

Made a sister post on stackoverflow here.

I discovered that the issue was that the provisioning profile being generated from XCode was using my personal ID instead of my organization ID so I had to turn off automatic signing and manually provide the correct provisioning profile. You can see more in detail the steps I took in my response to this StackOverflow post. Hope this helps someone :)

I also had this problem for a long time. Please do a deep dive on proper signing and notarization. Personally for me what fixed it was that I was providing the wrong provisioning profile so the notarization was failing. Turns out I needed a Distribution provisioning profile as opposed to a Developer provisioning profile. Also beware that if you sign an extension, package it within an app, then sign the app, then the extension signature will be overridden and possibly invalidated.

Have you found a solution? I would very much like to know if this implementation works! Though it appears, at least according to (this post)[https://developer.apple.com/forums/thread/739722], that only one works at a time :(

I believe I have solved this issue. I was missing an implementation of the evictItem() function.

Try URL.startAccessingSecurityScopedResource()! As described in the 2/2 File Provider video

Note: I also attempted removing the Sandbox entirely and had the same result.

I would also like to add that there are no crash reports for the extension in the Console App.

Got a response from tech support. Can't believe I missed this :P The root was not loading because enumeration (AKA populating a folder) is a testing operation. Therefore the FileProviderExtension was closing after ~5 seconds as it was doing nothing. Solution is to run the enumeration testing operation. Here is the response from support: "The system is waiting for you to run the enumeration process. You should be able to make it work by having a loop to periodically run at least the available children enumeration operations. The following code snippet runs the operations once. Since you use .interactive testing mode, you will need to create a loop so you can interactively pick and run an operation." if let fileProviderManager = NSFileProviderManager(for: domain) { do { let testingOperations = try fileProviderManager.listAvailableTestingOperations() for operation in testingOperations { if operation is NSFileProviderTestingChildrenEnumeration { try fileProviderManager.run(testingOperations) } } } catch { print(error) } }

I would suggest looking into the header file for NSFileProviderUserInteractions. It provides the following hooks: 'Copy' : copying item(s) within the same provider 'CopyOut' : copying item(s) out of the provider 'CopyIn' : copying item(s) into a folder/root of the provider You can access these hooks via the info.plist of you File Provider Extension. The header file provides an example of this. I have personally used it to display an alert when preventing forbidden user actions. I expect you could also use it to call custom functions. Hope this helps :)