diff --git a/CHANGES.rst b/CHANGES.rst
index 3be965fab..fcffdee2c 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -1,3 +1,12 @@
+Changes in 0.6.18 ()
+===============================================
+
+Improvements:
+ * Upgrade MatrixKit version ().
+ * RoomVC: Add a re-request keys button on message unable to decrypt (#1879).
+ 
+Bug fix:
+
 Changes in 0.6.17 (2018-06-01)
 ===============================================
 
diff --git a/Riot/Assets/en.lproj/Vector.strings b/Riot/Assets/en.lproj/Vector.strings
index 05f7ed41f..801e1e6d7 100644
--- a/Riot/Assets/en.lproj/Vector.strings
+++ b/Riot/Assets/en.lproj/Vector.strings
@@ -518,6 +518,8 @@
 "event_formatter_widget_removed" = "%@ widget removed by %@";
 "event_formatter_jitsi_widget_added" = "VoIP conference added by %@";
 "event_formatter_jitsi_widget_removed" = "VoIP conference removed by %@";
+"event_formatter_rerequest_keys_part1_link" = "Re-request encryption keys";
+"event_formatter_rerequest_keys_part2" = " from your other devices.";
 
 // Others
 "or" = "or";
@@ -622,3 +624,7 @@
 
 "deactivate_account_password_alert_title" = "Deactivate Account";
 "deactivate_account_password_alert_message" = "To continue, please enter your password";
+
+// Re-request confirmation dialog
+"rerequest_keys_alert_title" = "Request Sent";
+"rerequest_keys_alert_message" = "Please check your other devices for key share requests";
diff --git a/Riot/Utils/EventFormatter.h b/Riot/Utils/EventFormatter.h
index ba5d6a60c..d55c03257 100644
--- a/Riot/Utils/EventFormatter.h
+++ b/Riot/Utils/EventFormatter.h
@@ -16,6 +16,16 @@
 
 #import <MatrixKit/MatrixKit.h>
 
+/**
+ Link string used in attributed strings to mark a keys re-request action.
+ */
+FOUNDATION_EXPORT NSString *const kEventFormatterOnReRequestKeysLinkAction;
+
+/**
+ Parameters separator in the link string.
+ */
+FOUNDATION_EXPORT NSString *const kEventFormatterOnReRequestKeysLinkActionSeparator;
+
 /**
  `EventFormatter` class inherits from `MXKEventFormatter` to define Vector formatting
  */
diff --git a/Riot/Utils/EventFormatter.m b/Riot/Utils/EventFormatter.m
index ef1732e49..09f92f344 100644
--- a/Riot/Utils/EventFormatter.m
+++ b/Riot/Utils/EventFormatter.m
@@ -21,6 +21,13 @@
 
 #import "WidgetManager.h"
 
+#import "MXDecryptionResult.h"
+
+#pragma mark - Constants definitions
+
+NSString *const kEventFormatterOnReRequestKeysLinkAction = @"kEventFormatterOnReRequestKeysLinkAction";
+NSString *const kEventFormatterOnReRequestKeysLinkActionSeparator = @"/";
+
 @interface EventFormatter ()
 {
     /**
@@ -107,7 +114,40 @@
         }
     }
 
-    return [super attributedStringFromEvent:event withRoomState:roomState error:error];
+    NSAttributedString *attributedString = [super attributedStringFromEvent:event withRoomState:roomState error:error];
+
+    if (event.sentState == MXEventSentStateSent
+        && [event.decryptionError.domain isEqualToString:MXDecryptingErrorDomain]
+        && event.decryptionError.code == MXDecryptingErrorUnknownInboundSessionIdCode)
+    {
+        // Append to the displayed error an attibuted string with a tappable link 
+        // so that the user can try to fix the UTC
+        NSMutableAttributedString *attributedStringWithRerequestMessage = [attributedString mutableCopy];
+        [attributedStringWithRerequestMessage appendAttributedString:[[NSAttributedString alloc] initWithString:@"\n"]];
+
+        NSString *linkActionString = [NSString stringWithFormat:@"%@%@%@", kEventFormatterOnReRequestKeysLinkAction,
+                                      kEventFormatterOnReRequestKeysLinkActionSeparator,
+                                      event.eventId];
+
+        [attributedStringWithRerequestMessage appendAttributedString:
+         [[NSAttributedString alloc] initWithString:NSLocalizedStringFromTable(@"event_formatter_rerequest_keys_part1_link", @"Vector", nil)
+                                         attributes:@{
+                                                      NSLinkAttributeName: linkActionString,
+                                                      NSForegroundColorAttributeName: self.sendingTextColor,
+                                                      NSFontAttributeName: self.encryptedMessagesTextFont
+                                         }]];
+
+        [attributedStringWithRerequestMessage appendAttributedString:
+         [[NSAttributedString alloc] initWithString:NSLocalizedStringFromTable(@"event_formatter_rerequest_keys_part2", @"Vector", nil)
+                                         attributes:@{
+                                                      NSForegroundColorAttributeName: self.sendingTextColor,
+                                                      NSFontAttributeName: self.encryptedMessagesTextFont
+                                                      }]];
+
+        attributedString = attributedStringWithRerequestMessage;
+    }
+
+    return attributedString;
 }
 
 - (NSAttributedString*)attributedStringFromEvents:(NSArray<MXEvent*>*)events withRoomState:(MXRoomState*)roomState error:(MXKEventFormatterError*)error
diff --git a/Riot/ViewController/RoomViewController.m b/Riot/ViewController/RoomViewController.m
index 093f89e17..325e63ff1 100644
--- a/Riot/ViewController/RoomViewController.m
+++ b/Riot/ViewController/RoomViewController.m
@@ -117,6 +117,8 @@
 #import "WidgetPickerViewController.h"
 #import "StickerPickerViewController.h"
 
+#import "EventFormatter.h"
+
 @interface RoomViewController ()
 {
     // The expanded header
@@ -181,6 +183,9 @@
     
     // Observer kMXRoomSummaryDidChangeNotification to keep updated the missed discussion count
     id mxRoomSummaryDidChangeObserver;
+
+    // Observer for removing the re-request explanation/waiting dialog
+    id mxEventDidDecryptNotificationObserver;
     
     // The table view cell in which the read marker is displayed (nil by default).
     MXKRoomBubbleTableViewCell *readMarkerTableViewCell;
@@ -592,6 +597,12 @@
         [[NSNotificationCenter defaultCenter] removeObserver:mxRoomSummaryDidChangeObserver];
         mxRoomSummaryDidChangeObserver = nil;
     }
+
+    if (mxEventDidDecryptNotificationObserver)
+    {
+        [[NSNotificationCenter defaultCenter] removeObserver:mxEventDidDecryptNotificationObserver];
+        mxEventDidDecryptNotificationObserver = nil;
+    }
 }
 
 - (void)viewDidLayoutSubviews
@@ -1103,6 +1114,11 @@
         [[NSNotificationCenter defaultCenter] removeObserver:mxRoomSummaryDidChangeObserver];
         mxRoomSummaryDidChangeObserver = nil;
     }
+    if (mxEventDidDecryptNotificationObserver)
+    {
+        [[NSNotificationCenter defaultCenter] removeObserver:mxEventDidDecryptNotificationObserver];
+        mxEventDidDecryptNotificationObserver = nil;
+    }
     
     [self removeCallNotificationsListeners];
     [self removeWidgetNotificationsListeners];
@@ -2680,6 +2696,20 @@
             NSString *fragment = [NSString stringWithFormat:@"/group/%@", [absoluteURLString stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];
             [[AppDelegate theDelegate] handleUniversalLinkFragment:fragment];
         }
+        else if ([absoluteURLString hasPrefix:kEventFormatterOnReRequestKeysLinkAction])
+        {
+            NSArray<NSString*> *arguments = [absoluteURLString componentsSeparatedByString:kEventFormatterOnReRequestKeysLinkActionSeparator];
+            if (arguments.count > 1)
+            {
+                NSString *eventId = arguments[1];
+                MXEvent *event = [self.roomDataSource eventWithEventId:eventId];
+
+                if (event)
+                {
+                    [self reRequestKeysAndShowExplanationAlert:event];
+                }
+            }
+        }
     }
     
     return shouldDoAction;
@@ -4582,5 +4612,57 @@
     [self presentViewController:currentAlert animated:YES completion:nil];
 }
 
+#pragma mark - Re-request encryption keys
+
+- (void)reRequestKeysAndShowExplanationAlert:(MXEvent*)event
+{
+    MXWeakify(self);
+    __block UIAlertController *alert;
+
+    // Make the re-request
+    [self.mainSession.crypto reRequestRoomKeyForEvent:event];
+
+    // Observe kMXEventDidDecryptNotification to remove automatically the dialog
+    // if the user has shared the keys from another device
+    mxEventDidDecryptNotificationObserver = [[NSNotificationCenter defaultCenter] addObserverForName:kMXEventDidDecryptNotification object:nil queue:[NSOperationQueue mainQueue] usingBlock:^(NSNotification *notif) {
+        MXStrongifyAndReturnIfNil(self);
+
+        MXEvent *decryptedEvent = notif.object;
+
+        if ([decryptedEvent.eventId isEqualToString:event.eventId])
+        {
+            [[NSNotificationCenter defaultCenter] removeObserver:self->mxEventDidDecryptNotificationObserver];
+            self->mxEventDidDecryptNotificationObserver = nil;
+
+            if (self->currentAlert == alert)
+            {
+                [self->currentAlert dismissViewControllerAnimated:YES completion:nil];
+                self->currentAlert = nil;
+            }
+        }
+    }];
+
+    // Show the explanation dialog
+    alert = [UIAlertController alertControllerWithTitle:NSLocalizedStringFromTable(@"rerequest_keys_alert_title", @"Vector", nil)
+                                                       message:NSLocalizedStringFromTable(@"rerequest_keys_alert_message", @"Vector", nil)
+                                                preferredStyle:UIAlertControllerStyleAlert];
+    currentAlert = alert;
+
+
+    [alert addAction:[UIAlertAction actionWithTitle:[NSBundle mxk_localizedStringForKey:@"ok"]
+                                                     style:UIAlertActionStyleDefault
+                                                   handler:^(UIAlertAction * action)
+                             {
+                                 MXStrongifyAndReturnIfNil(self);
+
+                                 [[NSNotificationCenter defaultCenter] removeObserver:self->mxEventDidDecryptNotificationObserver];
+                                 self->mxEventDidDecryptNotificationObserver = nil;
+
+                                 self->currentAlert = nil;
+                             }]];
+
+    [self presentViewController:currentAlert animated:YES completion:nil];
+}
+
 @end