diff --git a/Signal/src/ViewControllers/RegistrationViewController.m b/Signal/src/ViewControllers/RegistrationViewController.m
index 51bdff0d4..af48126c0 100644
--- a/Signal/src/ViewControllers/RegistrationViewController.m
+++ b/Signal/src/ViewControllers/RegistrationViewController.m
@@ -359,12 +359,6 @@ NSString *const kKeychainKey_LastRegisteredPhoneNumber = @"kKeychainKey_LastRegi
     [self presentViewController:navigationController animated:YES completion:[UIUtil modalCompletionBlock]];
 }
 
-- (void)presentInvalidCountryCodeError {
-    [OWSAlerts showAlertWithTitle:NSLocalizedString(@"REGISTER_CC_ERR_ALERT_VIEW_TITLE", @"")
-                          message:NSLocalizedString(@"REGISTER_CC_ERR_ALERT_VIEW_MESSAGE", @"")
-                      buttonTitle:CommonStrings.dismissButton];
-}
-
 - (void)backgroundTapped:(UIGestureRecognizer *)sender
 {
     if (sender.state == UIGestureRecognizerStateRecognized) {
diff --git a/Signal/translations/en.lproj/Localizable.strings b/Signal/translations/en.lproj/Localizable.strings
index d8735bc0c..a864628ea 100644
--- a/Signal/translations/en.lproj/Localizable.strings
+++ b/Signal/translations/en.lproj/Localizable.strings
@@ -1273,12 +1273,6 @@
 /* No comment provided by engineer. */
 "RATING_TITLE" = "Support Signal!";
 
-/* No comment provided by engineer. */
-"REGISTER_CC_ERR_ALERT_VIEW_MESSAGE" = "Please enter a valid country code";
-
-/* No comment provided by engineer. */
-"REGISTER_CC_ERR_ALERT_VIEW_TITLE" = "Country Code Error";
-
 /* No comment provided by engineer. */
 "REGISTER_CONTACTS_WELCOME" = "Welcome!";
 
@@ -1570,6 +1564,9 @@
 /* Title indicating that the share extension cannot be used until the main app has been launched at least once. */
 "SHARE_EXTENSION_NOT_YET_MIGRATED_TITLE" = "Not Ready";
 
+/* Shown when trying to share content to a Signal user for the share extension. Followed by failure details. */
+"SHARE_EXTENSION_UNABLE_TO_BUILD_ATTACHMENT_ALERT_TITLE" = "Unable to Prepare Attachment";
+
 /* Action sheet item */
 "SHOW_SAFETY_NUMBER_ACTION" = "Show New Safety Number";
 
diff --git a/SignalMessaging/attachments/SendExternalFileViewController.m b/SignalMessaging/attachments/SendExternalFileViewController.m
index 3e60bf09f..a68a55ed2 100644
--- a/SignalMessaging/attachments/SendExternalFileViewController.m
+++ b/SignalMessaging/attachments/SendExternalFileViewController.m
@@ -200,7 +200,7 @@ NS_ASSUME_NONNULL_BEGIN
     [ThreadUtil sendMessageWithAttachment:self.attachment inThread:self.thread messageSender:self.messageSender];
 
     // FIXME SHARINGEXTENSION
-    // Show loading screen and dismiss entire share extnesion once entirely complete
+    // Show loading screen and dismiss entire share extension once entirely complete
     [self.navigationController popViewControllerAnimated:YES];
 }
 
diff --git a/SignalMessaging/views/OWSAlerts.swift b/SignalMessaging/views/OWSAlerts.swift
index cb12ea4b9..898830b0f 100644
--- a/SignalMessaging/views/OWSAlerts.swift
+++ b/SignalMessaging/views/OWSAlerts.swift
@@ -34,13 +34,13 @@ import Foundation
     }
 
     @objc
-    public class func showAlert(withTitle title: String, message: String? = nil, buttonTitle: String? = nil) {
+    public class func showAlert(withTitle title: String, message: String? = nil, buttonTitle: String? = nil, buttonAction: ((UIAlertAction) -> Void)? = nil) {
         assert(title.count > 0)
 
         let actionTitle = buttonTitle ?? NSLocalizedString("OK", comment: "")
 
         let alert = UIAlertController(title: title, message: message, preferredStyle: .alert)
-        alert.addAction(UIAlertAction(title: actionTitle, style: .default, handler: nil))
+        alert.addAction(UIAlertAction(title: actionTitle, style: .default, handler: buttonAction))
         CurrentAppContext().frontmostViewController()?.present(alert, animated: true, completion: nil)
     }
 
diff --git a/SignalServiceKit/src/Messages/OWSMessageSender.m b/SignalServiceKit/src/Messages/OWSMessageSender.m
index 74f822033..d65ef72d8 100644
--- a/SignalServiceKit/src/Messages/OWSMessageSender.m
+++ b/SignalServiceKit/src/Messages/OWSMessageSender.m
@@ -242,9 +242,8 @@ NSUInteger const OWSSendMessageOperationMaxRetries = 4;
     AssertIsOnMainThread();
 
     // Should only be sent once per operation
-    // FIXME SHARINGEXTENSION
-//    OWSAssert(_backgroundTaskIdentifier == UIBackgroundTaskInvalid);
-//    OWSAssert(backgroundTaskIdentifier != UIBackgroundTaskInvalid);
+    OWSAssert(!CurrentAppContext().isMainApp || _backgroundTaskIdentifier == UIBackgroundTaskInvalid);
+    OWSAssert(!CurrentAppContext().isMainApp || backgroundTaskIdentifier != UIBackgroundTaskInvalid);
 
     _backgroundTaskIdentifier = backgroundTaskIdentifier;
 }
diff --git a/SignalShareExtension/ShareViewController.swift b/SignalShareExtension/ShareViewController.swift
index 8517e32c2..20d526c8a 100644
--- a/SignalShareExtension/ShareViewController.swift
+++ b/SignalShareExtension/ShareViewController.swift
@@ -362,6 +362,11 @@ public class ShareViewController: UINavigationController, SAELoadViewDelegate, S
             self.pushViewController(conversationPicker, animated: false)
             Logger.info("presented conversation picker with attachment")
         }.catch { error in
+            OWSAlerts.showAlert(withTitle: NSLocalizedString("SHARE_EXTENSION_UNABLE_TO_BUILD_ATTACHMENT_ALERT_TITLE", comment: "Shown when trying to share content to a Signal user for the share extension. Followed by failure details."),
+                                message: error.localizedDescription,
+                                buttonTitle: CommonStrings.cancelButton) { _ in
+                                    self.shareExtensionWasCancelled()
+            }
             owsFail("\(self.logTag) building attachment failed with error: \(error)")
         }.retainUntilComplete()
     }