 							case .success:
 								break
 							case .failure(let error):
-								NSApplication.shared.presentError(error)
+								if let accountError = error as? AccountError, case .createErrorNotFound = accountError {
+									notFoundFeedNames.append(feed.nameForDisplay)
+								} else {
+									NSApplication.shared.presentError(error)
+								}
 							}
 						}
 					}
 				}
 				group.notify(queue: DispatchQueue.main) {
 					completion()
+					if !notFoundFeedNames.isEmpty {
+						NSApplication.shared.presentError(SidebarOutlineDataSourceError.createErrorNotFound(notFoundFeedNames))
+					}
 				}
 			case .failure(let error):
 				NSApplication.shared.presentError(error)

			switch result {
			case .success(let destinationFolder):
				let group = DispatchGroup()
				for feed in folder.topLevelWebFeeds {
					if let existingFeed = destinationAccount.existingWebFeed(withURL: feed.url) {
						group.enter()

import Articles
import RSCore
import Account

public enum SidebarOutlineDataSourceError: LocalizedError {
	case createErrorNotFound([String])
	
	public var errorDescription: String? {
		switch self {
		case .createErrorNotFound(let feedNames):
			let message = NSLocalizedString("The following feeds could not be added because they could not be found:\n", comment: "Not found")
			return "\(message)\(feedNames.joined(separator: ", "))"
		}
	}
}

@objc final class SidebarOutlineDataSource: NSObject, NSOutlineViewDataSource {

