diff --git a/SignalServiceKit/src/Contacts/SignalRecipient.h b/SignalServiceKit/src/Contacts/SignalRecipient.h
index e1ef16f7b..c781bc46a 100644
--- a/SignalServiceKit/src/Contacts/SignalRecipient.h
+++ b/SignalServiceKit/src/Contacts/SignalRecipient.h
@@ -29,8 +29,7 @@ NS_ASSUME_NONNULL_BEGIN
 
 - (void)addDevicesToRegisteredRecipient:(NSSet *)devices
                             transaction:(YapDatabaseReadWriteTransaction *)transaction;
-- (void)removeDevicesFromRegisteredRecipient:(NSSet *)devices
-                                 transaction:(YapDatabaseReadWriteTransaction *)transaction;
+- (void)removeDevicesFromRecipient:(NSSet *)devices transaction:(YapDatabaseReadWriteTransaction *)transaction;
 
 - (NSString *)recipientId;
 
diff --git a/SignalServiceKit/src/Contacts/SignalRecipient.m b/SignalServiceKit/src/Contacts/SignalRecipient.m
index db163a015..993a3bba8 100644
--- a/SignalServiceKit/src/Contacts/SignalRecipient.m
+++ b/SignalServiceKit/src/Contacts/SignalRecipient.m
@@ -149,20 +149,23 @@ NS_ASSUME_NONNULL_BEGIN
     [latest saveWithTransaction_internal:transaction];
 }
 
-- (void)removeDevicesFromRegisteredRecipient:(NSSet *)devices transaction:(YapDatabaseReadWriteTransaction *)transaction
+- (void)removeDevicesFromRecipient:(NSSet *)devices transaction:(YapDatabaseReadWriteTransaction *)transaction
 {
     OWSAssert(transaction);
     OWSAssert(devices.count > 0);
 
     [self removeDevices:devices];
 
-    SignalRecipient *latest =
-        [SignalRecipient markRecipientAsRegisteredAndGet:self.recipientId transaction:transaction];
+    SignalRecipient *_Nullable latest =
+        [SignalRecipient registeredRecipientForRecipientId:self.recipientId transaction:transaction];
 
+    if (!latest) {
+        return;
+    }
     if (![devices intersectsSet:latest.devices.set]) {
         return;
     }
-    DDLogDebug(@"%@ removing devices: %@, from recipient: %@", self.logTag, devices, latest.recipientId);
+    DDLogDebug(@"%@ removing devices: %@, from registered recipient: %@", self.logTag, devices, latest.recipientId);
 
     [latest removeDevices:devices];
     [latest saveWithTransaction_internal:transaction];
diff --git a/SignalServiceKit/src/Messages/Attachments/TSAttachment.m b/SignalServiceKit/src/Messages/Attachments/TSAttachment.m
index 1d4e0957d..2d3d1465c 100644
--- a/SignalServiceKit/src/Messages/Attachments/TSAttachment.m
+++ b/SignalServiceKit/src/Messages/Attachments/TSAttachment.m
@@ -71,7 +71,6 @@ NSUInteger const TSAttachmentSchemaVersion = 4;
         contentType = OWSMimeTypeApplicationOctetStream;
     }
     OWSAssert(contentType.length > 0);
-    OWSAssert(byteCount > 0);
 
     self = [super init];
     if (!self) {
diff --git a/SignalServiceKit/src/Messages/OWSMessageSender.m b/SignalServiceKit/src/Messages/OWSMessageSender.m
index f49823bd9..3e10fd95a 100644
--- a/SignalServiceKit/src/Messages/OWSMessageSender.m
+++ b/SignalServiceKit/src/Messages/OWSMessageSender.m
@@ -1166,7 +1166,7 @@ NSString *const OWSMessageSenderRateLimitedException = @"RateLimitedException";
     }
 
     [self.dbConnection
-        asyncReadWriteWithBlock:^(YapDatabaseReadWriteTransaction * transaction) {
+        readWriteWithBlock:^(YapDatabaseReadWriteTransaction *transaction) {
             if (extraDevices.count < 1 && missingDevices.count < 1) {
                 OWSProdFail([OWSAnalyticsEvents messageSenderErrorNoMissingOrExtraDevices]);
             }
@@ -1179,8 +1179,7 @@ NSString *const OWSMessageSenderRateLimitedException = @"RateLimitedException";
                                                  protocolContext:transaction];
                 }
 
-                [recipient removeDevicesFromRegisteredRecipient:[NSSet setWithArray:extraDevices]
-                             transaction:transaction];
+                [recipient removeDevicesFromRecipient:[NSSet setWithArray:extraDevices] transaction:transaction];
             }
 
             if (missingDevices && missingDevices.count > 0) {
@@ -1279,11 +1278,9 @@ NSString *const OWSMessageSenderRateLimitedException = @"RateLimitedException";
             }
         } @catch (NSException *exception) {
             if ([exception.name isEqualToString:OWSMessageSenderInvalidDeviceException]) {
-                [self.dbConnection
-                 asyncReadWriteWithBlock:^(YapDatabaseReadWriteTransaction * transaction) {
-                     [recipient removeDevicesFromRegisteredRecipient:[NSSet setWithObject:deviceNumber]
-                                  transaction:transaction];
-                 }];
+                [self.dbConnection readWriteWithBlock:^(YapDatabaseReadWriteTransaction *transaction) {
+                    [recipient removeDevicesFromRecipient:[NSSet setWithObject:deviceNumber] transaction:transaction];
+                }];
             } else {
                 @throw exception;
             }
@@ -1332,9 +1329,6 @@ NSString *const OWSMessageSenderRateLimitedException = @"RateLimitedException";
                 DDLogError(@"Server replied to PreKeyBundle request with error: %@", error);
                 NSHTTPURLResponse *response = (NSHTTPURLResponse *)task.response;
                 if (response.statusCode == 404) {
-                    [recipient removeDevicesFromRegisteredRecipient:[NSSet setWithObject:deviceNumber]
-                                                        transaction:transaction];
-
                     // Can't throw exception from within callback as it's probabably a different thread.
                     exception = [NSException exceptionWithName:OWSMessageSenderInvalidDeviceException
                                                         reason:@"Device not registered"