diff --git a/NearbyShare/Connection/NearbyConnectionManager.swift b/NearbyShare/Connection/NearbyConnectionManager.swift
index e5e6c58..8c5ecfd 100644
--- a/NearbyShare/Connection/NearbyConnectionManager.swift
+++ b/NearbyShare/Connection/NearbyConnectionManager.swift
@@ -33,6 +33,7 @@ public class NearbyConnectionManager: NSObject, NetServiceDelegate, InboundNearb
     private var outboundAppDelegates: [OutboundAppDelegate] = []
     private var inboundAppDelegates: [InboundAppDelegate] = []
     private var outgoingTransfers: [String: OutgoingTransferInfo] = [:]
+    private var pendingOutgoingTransferPreparations: [String: UUID] = [:]
     private var startedDeviceDiscovery = false
     private var startedAdvertising = false { didSet { informAboutStatus() }}
     private var browsers: [NWBrowser] = []
@@ -515,6 +516,7 @@ public class NearbyConnectionManager: NSObject, NetServiceDelegate, InboundNearb
         if let transfer = incomingConnections[id] {
             transfer.cancel()
         }
+        pendingOutgoingTransferPreparations.removeValue(forKey: id)
         if let info = outgoingTransfers[id] {
             info.connection.cancel()
         }
@@ -699,28 +701,60 @@ public class NearbyConnectionManager: NSObject, NetServiceDelegate, InboundNearb
     }
     
     
-    public func startOutgoingTransfer(deviceID: String, delegate: OutboundAppDelegate, urls: [URL], textToSend: String?) {
+    public func startOutgoingTransfer(
+        deviceID: String,
+        delegate: OutboundAppDelegate,
+        urls: [URL],
+        textToSend: String?,
+        preparationFinished: (() -> Void)? = nil
+    ) {
         log("Starting outgoing transfer to \(deviceID)")
-        guard let info = foundServices[deviceID] else { return }
-        
-        do {
-            let localUrls = try saveFilesToTemp(urls: urls)
-            
-            let tcp = NWProtocolTCP.Options()
-            tcp.noDelay = true
-            let nwconn = NWConnection(to: info.service.endpoint, using: NWParameters(tls: .none, tcp: tcp))
-            
-            let conn = OutboundNearbyConnection(connection: nwconn, id: deviceID, urlsToSend: localUrls, textToSend: textToSend)
-            conn.delegate = self
-            conn.qrCodePrivateKey = qrCodePrivateKey
-            
-            let transfer = OutgoingTransferInfo(service: info.service, device: info.device!, connection: conn, delegate: delegate)
-            outgoingTransfers[deviceID] = transfer
-            conn.start()
-        } catch {
-            log("[NearbyConnectionManager] Error storing URLs: \(error)")
-            outboundAppDelegates.forEach { delegate in
-                delegate.connectionFailed(error: error)
+        guard foundServices[deviceID] != nil else { return }
+
+        let preparationID = UUID()
+        pendingOutgoingTransferPreparations[deviceID] = preparationID
+
+        DispatchQueue.global(qos: .userInitiated).async { [weak self, weak delegate] in
+            guard let self else { return }
+
+            do {
+                let localUrls = try self.saveFilesToTemp(urls: urls)
+
+                DispatchQueue.main.async {
+                    guard let info = self.foundServices[deviceID],
+                          self.pendingOutgoingTransferPreparations[deviceID] == preparationID else {
+                        return
+                    }
+
+                    self.pendingOutgoingTransferPreparations.removeValue(forKey: deviceID)
+                    guard let delegate else { return }
+
+                    preparationFinished?()
+
+                    let tcp = NWProtocolTCP.Options()
+                    tcp.noDelay = true
+                    let nwconn = NWConnection(to: info.service.endpoint, using: NWParameters(tls: .none, tcp: tcp))
+
+                    let conn = OutboundNearbyConnection(connection: nwconn, id: deviceID, urlsToSend: localUrls, textToSend: textToSend)
+                    conn.delegate = self
+                    conn.qrCodePrivateKey = self.qrCodePrivateKey
+
+                    let transfer = OutgoingTransferInfo(service: info.service, device: info.device!, connection: conn, delegate: delegate)
+                    self.outgoingTransfers[deviceID] = transfer
+                    conn.start()
+                }
+            } catch {
+                log("[NearbyConnectionManager] Error storing URLs: \(error)")
+                DispatchQueue.main.async {
+                    guard self.pendingOutgoingTransferPreparations[deviceID] == preparationID else {
+                        return
+                    }
+
+                    self.pendingOutgoingTransferPreparations.removeValue(forKey: deviceID)
+                    self.outboundAppDelegates.forEach { delegate in
+                        delegate.connectionFailed(error: error)
+                    }
+                }
             }
         }
     }
diff --git a/ShareExtension/ShareViewController.swift b/ShareExtension/ShareViewController.swift
index 496be44..1061cd9 100644
--- a/ShareExtension/ShareViewController.swift
+++ b/ShareExtension/ShareViewController.swift
@@ -259,37 +259,43 @@ class ShareViewController: NSViewController, OutboundAppDelegate {
         chosenDevice = device
         
         runAfter(seconds: 0.3) {
-            NearbyConnectionManager.shared.startOutgoingTransfer(deviceID: device.id!, delegate: self, urls: self.urls, textToSend: self.textToSend)
-            
-            self.progressState?.stringValue = "Connecting".localized()
-            
-            let timeoutAlert = DispatchWorkItem {
-                if !self.connectionEstablished {
-                    AudioManager.playErrorSound()
-                    let alert = NSAlert()
-                    alert.alertStyle = .critical
+            NearbyConnectionManager.shared.startOutgoingTransfer(
+                deviceID: device.id!,
+                delegate: self,
+                urls: self.urls,
+                textToSend: self.textToSend,
+                preparationFinished: {
+                    self.progressState?.stringValue = "Connecting".localized()
                     
-                    alert.messageText = "TimeoutTitle".localized()
-                    
-                    if #available(macOS 15.0, *) {
-                        alert.informativeText = "TimeoutDescription".localized()
-                        alert.addButton(withTitle: "TimeoutButton".localized())
-                        alert.addButton(withTitle: "CloseAlert".localized())
-                    } else {
-                        alert.informativeText = "TimeoutDescriptionLegacy".localized()
-                        alert.addButton(withTitle: "TimeoutButtonLegacy".localized())
-                    }
-                    
-                    alert.beginSheetModal(for: self.view.window!) { response in
-                        if #available(macOS 15.0, *), response == .alertFirstButtonReturn {
-                            openPrivacyAndSecuritySettings()
+                    let timeoutAlert = DispatchWorkItem {
+                        if !self.connectionEstablished {
+                            AudioManager.playErrorSound()
+                            let alert = NSAlert()
+                            alert.alertStyle = .critical
+                            
+                            alert.messageText = "TimeoutTitle".localized()
+                            
+                            if #available(macOS 15.0, *) {
+                                alert.informativeText = "TimeoutDescription".localized()
+                                alert.addButton(withTitle: "TimeoutButton".localized())
+                                alert.addButton(withTitle: "CloseAlert".localized())
+                            } else {
+                                alert.informativeText = "TimeoutDescriptionLegacy".localized()
+                                alert.addButton(withTitle: "TimeoutButtonLegacy".localized())
+                            }
+                            
+                            alert.beginSheetModal(for: self.view.window!) { response in
+                                if #available(macOS 15.0, *), response == .alertFirstButtonReturn {
+                                    openPrivacyAndSecuritySettings()
+                                }
+                            }
                         }
                     }
+                    
+                    self.timeoutDispatchWorkItem = timeoutAlert
+                    DispatchQueue.main.asyncAfter(deadline: .now() + 10.0, execute: timeoutAlert)
                 }
-            }
-            
-            self.timeoutDispatchWorkItem = timeoutAlert
-            DispatchQueue.main.asyncAfter(deadline: .now() + 10.0, execute: timeoutAlert) 
+            )
         }
     }