diff --git a/app/src/main/java/org/linphone/ui/main/chat/fragment/ConversationInfoFragment.kt b/app/src/main/java/org/linphone/ui/main/chat/fragment/ConversationInfoFragment.kt
index f85dd1c19..e8509c7f1 100644
--- a/app/src/main/java/org/linphone/ui/main/chat/fragment/ConversationInfoFragment.kt
+++ b/app/src/main/java/org/linphone/ui/main/chat/fragment/ConversationInfoFragment.kt
@@ -226,6 +226,7 @@ class ConversationInfoFragment : SlidingPaneChildFragment() {
 
             val dialog = DialogUtils.getSetOrEditGroupSubjectDialog(
                 requireContext(),
+                viewLifecycleOwner,
                 model
             )
 
@@ -238,11 +239,17 @@ class ConversationInfoFragment : SlidingPaneChildFragment() {
 
             model.confirmEvent.observe(viewLifecycleOwner) {
                 it.consume { newSubject ->
-                    Log.i(
-                        "$TAG Conversation subject edit confirmed, new subject is [$newSubject] (old was [$currentSubject])"
-                    )
-                    viewModel.updateSubject(newSubject)
-                    dialog.dismiss()
+                    if (newSubject.isNotEmpty()) {
+                        Log.i(
+                            "$TAG Conversation subject edit confirmed, new subject is [$newSubject] (old was [$currentSubject])"
+                        )
+                        viewModel.updateSubject(newSubject)
+                        dialog.dismiss()
+                    } else {
+                        val message = getString(R.string.conversation_invalid_empty_subject_toast)
+                        val icon = R.drawable.warning_circle
+                        (requireActivity() as GenericActivity).showRedToast(message, icon)
+                    }
                 }
             }
 
diff --git a/app/src/main/java/org/linphone/ui/main/chat/fragment/StartConversationFragment.kt b/app/src/main/java/org/linphone/ui/main/chat/fragment/StartConversationFragment.kt
index 8e7340dca..2745f8977 100644
--- a/app/src/main/java/org/linphone/ui/main/chat/fragment/StartConversationFragment.kt
+++ b/app/src/main/java/org/linphone/ui/main/chat/fragment/StartConversationFragment.kt
@@ -129,6 +129,7 @@ class StartConversationFragment : GenericAddressPickerFragment() {
 
         val dialog = DialogUtils.getSetOrEditGroupSubjectDialog(
             requireContext(),
+            viewLifecycleOwner,
             model
         )
 
diff --git a/app/src/main/java/org/linphone/ui/main/fragment/GroupSetOrEditSubjectDialogModel.kt b/app/src/main/java/org/linphone/ui/main/fragment/GroupSetOrEditSubjectDialogModel.kt
index 860053294..7a36c7063 100644
--- a/app/src/main/java/org/linphone/ui/main/fragment/GroupSetOrEditSubjectDialogModel.kt
+++ b/app/src/main/java/org/linphone/ui/main/fragment/GroupSetOrEditSubjectDialogModel.kt
@@ -20,6 +20,7 @@
 package org.linphone.ui.main.fragment
 
 import androidx.annotation.UiThread
+import androidx.lifecycle.MediatorLiveData
 import androidx.lifecycle.MutableLiveData
 import org.linphone.utils.Event
 
@@ -35,7 +36,12 @@ class GroupSetOrEditSubjectDialogModel @UiThread constructor(
 
     val confirmEvent = MutableLiveData<Event<String>>()
 
+    val emptySubject = MediatorLiveData<Boolean>()
+
     init {
+        emptySubject.addSource(subject) { subject ->
+            emptySubject.value = subject.isEmpty()
+        }
         subject.value = initialSubject
     }
 
@@ -46,6 +52,8 @@ class GroupSetOrEditSubjectDialogModel @UiThread constructor(
 
     @UiThread
     fun confirm() {
-        confirmEvent.value = Event(subject.value.orEmpty())
+        val newSubject = subject.value.orEmpty()
+        emptySubject.value = newSubject.isEmpty()
+        confirmEvent.value = Event(newSubject)
     }
 }
diff --git a/app/src/main/java/org/linphone/ui/main/history/fragment/StartCallFragment.kt b/app/src/main/java/org/linphone/ui/main/history/fragment/StartCallFragment.kt
index f1f3365ba..9fa539662 100644
--- a/app/src/main/java/org/linphone/ui/main/history/fragment/StartCallFragment.kt
+++ b/app/src/main/java/org/linphone/ui/main/history/fragment/StartCallFragment.kt
@@ -180,6 +180,7 @@ class StartCallFragment : GenericAddressPickerFragment() {
 
         val dialog = DialogUtils.getSetOrEditGroupSubjectDialog(
             requireContext(),
+            viewLifecycleOwner,
             model
         )
 
diff --git a/app/src/main/java/org/linphone/utils/DialogUtils.kt b/app/src/main/java/org/linphone/utils/DialogUtils.kt
index cc02556e6..2ba5b061e 100644
--- a/app/src/main/java/org/linphone/utils/DialogUtils.kt
+++ b/app/src/main/java/org/linphone/utils/DialogUtils.kt
@@ -258,6 +258,7 @@ class DialogUtils {
         @UiThread
         fun getSetOrEditGroupSubjectDialog(
             context: Context,
+            lifecycleOwner: LifecycleOwner,
             viewModel: GroupSetOrEditSubjectDialogModel
         ): Dialog {
             val binding: DialogSetOrEditGroupSubjectBindingImpl = DataBindingUtil.inflate(
@@ -266,6 +267,7 @@ class DialogUtils {
                 null,
                 false
             )
+            binding.lifecycleOwner = lifecycleOwner
             binding.viewModel = viewModel
             // For some reason, binding.subject triggers an error on Android Studio...
             binding.root.findViewById<AppCompatEditText>(R.id.subject)?.requestFocus()
diff --git a/app/src/main/res/layout/dialog_set_or_edit_group_subject.xml b/app/src/main/res/layout/dialog_set_or_edit_group_subject.xml
index 196887c24..e1ff1bd5b 100644
--- a/app/src/main/res/layout/dialog_set_or_edit_group_subject.xml
+++ b/app/src/main/res/layout/dialog_set_or_edit_group_subject.xml
@@ -67,7 +67,7 @@
             android:textSize="14sp"
             android:textColor="?attr/color_main2_600"
             android:maxLines="1"
-            android:background="@drawable/edit_text_background"
+            android:background="@{viewModel.emptySubject ? @drawable/shape_edit_text_error_background : @drawable/edit_text_background, default=@drawable/edit_text_background}"
             android:inputType="text|textCapSentences"
             app:layout_constraintHorizontal_bias="0"
             app:layout_constraintWidth_max="@dimen/text_input_max_width"
@@ -76,6 +76,19 @@
             app:layout_constraintEnd_toEndOf="@id/dialog_background"
             app:layout_constraintTop_toBottomOf="@id/title"/>
 
+        <androidx.appcompat.widget.AppCompatTextView
+            style="@style/default_text_style_600"
+            android:id="@+id/subject_error"
+            android:layout_width="0dp"
+            android:layout_height="wrap_content"
+            android:text="@string/conversation_dialog_subject_cant_be_empty_error"
+            android:textSize="13sp"
+            android:textColor="?attr/color_danger_500"
+            android:visibility="@{viewModel.emptySubject ? View.VISIBLE : View.GONE, default=gone}"
+            app:layout_constraintTop_toBottomOf="@id/subject"
+            app:layout_constraintStart_toStartOf="@id/subject"
+            app:layout_constraintEnd_toEndOf="@id/subject"/>
+
         <androidx.appcompat.widget.AppCompatTextView
             android:onClick="@{() -> viewModel.dismiss()}"
             style="@style/secondary_button_label_style"
@@ -100,6 +113,7 @@
             android:layout_marginTop="16dp"
             android:layout_marginStart="15dp"
             android:layout_marginEnd="15dp"
+            android:enabled="@{!viewModel.emptySubject}"
             android:text="@string/conversation_dialog_edit_subject_confirm_button"
             app:layout_constraintStart_toStartOf="@id/dialog_background"
             app:layout_constraintEnd_toEndOf="@id/dialog_background"
diff --git a/app/src/main/res/values-fr/strings.xml b/app/src/main/res/values-fr/strings.xml
index 04ce2d16d..89bf236ca 100644
--- a/app/src/main/res/values-fr/strings.xml
+++ b/app/src/main/res/values-fr/strings.xml
@@ -440,6 +440,7 @@
     <string name="conversation_maximum_number_of_attachments_reached">Nombre maximum de fichiers atteint !</string>
     <string name="conversation_dialog_set_subject">Nommer la conversation</string>
     <string name="conversation_dialog_edit_subject">Renommer la conversation</string>
+    <string name="conversation_dialog_subject_cant_be_empty_error">Un nom est obligatoire</string>
     <string name="conversation_dialog_subject_hint">Nom de la conversation</string>
     <string name="conversation_dialog_edit_subject_confirm_button">Confirmer</string>
     <string name="conversation_dialog_open_or_export_file_title">Ouvrir ou sauvegarder le fichier ?</string>
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index dc85fa8d9..643cf0de1 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -478,6 +478,7 @@
     <string name="conversation_maximum_number_of_attachments_reached">Maximum number of attachments reached!</string>
     <string name="conversation_dialog_set_subject">Set conversation subject</string>
     <string name="conversation_dialog_edit_subject">Edit conversation subject</string>
+    <string name="conversation_dialog_subject_cant_be_empty_error">Subject is mandatory</string>
     <string name="conversation_dialog_subject_hint">Conversation subject</string>
     <string name="conversation_dialog_edit_subject_confirm_button">Confirm</string>
     <string name="conversation_dialog_open_or_export_file_title">Open or export file?</string>