diff --git a/lib/src/main/java/org/asamk/signal/manager/Manager.java b/lib/src/main/java/org/asamk/signal/manager/Manager.java
index d8a1f563..8e409185 100644
--- a/lib/src/main/java/org/asamk/signal/manager/Manager.java
+++ b/lib/src/main/java/org/asamk/signal/manager/Manager.java
@@ -2365,9 +2365,9 @@ public class Manager implements Closeable {
 
         final var profileEntry = account.getProfileStore().getProfileEntry(address);
         if (profileEntry != null && profileEntry.getProfile() != null) {
-            return profileEntry.getProfile().getDisplayName();
+            String name = profileEntry.getProfile().getDisplayName();
+            return name==null?"":name;
         }
-
         return null;
     }
 
diff --git a/src/main/java/org/asamk/signal/ReceiveMessageHandler.java b/src/main/java/org/asamk/signal/ReceiveMessageHandler.java
index 6df283f3..b59eeee2 100644
--- a/src/main/java/org/asamk/signal/ReceiveMessageHandler.java
+++ b/src/main/java/org/asamk/signal/ReceiveMessageHandler.java
@@ -665,7 +665,7 @@ public class ReceiveMessageHandler implements Manager.ReceiveMessageHandler {
     private String formatContact(SignalServiceAddress address) {
         final var number = address.getLegacyIdentifier();
         var name = m.getContactOrProfileName(number);
-        if (name == null) {
+        if (name == null || name.isEmpty()) {
             return number;
         } else {
             return MessageFormatter.arrayFormat("“{}” {}", new Object[]{name, number}).getMessage();
diff --git a/src/main/java/org/asamk/signal/dbus/DbusSignalImpl.java b/src/main/java/org/asamk/signal/dbus/DbusSignalImpl.java
index fe416c66..24a90662 100644
--- a/src/main/java/org/asamk/signal/dbus/DbusSignalImpl.java
+++ b/src/main/java/org/asamk/signal/dbus/DbusSignalImpl.java
@@ -333,6 +333,9 @@ public class DbusSignalImpl implements Signal {
     public void joinGroup(final String groupLink) {
         try {
             final var linkUrl = GroupInviteLinkUrl.fromUri(groupLink);
+            if (linkUrl == null) {
+                throw new Error.Failure("Group link is invalid:");
+            }
             m.joinGroup(linkUrl);
         } catch (GroupInviteLinkUrl.InvalidGroupLinkException | GroupLinkNotActiveException e) {
             throw new Error.Failure("Group link is invalid: " + e.getMessage());