diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/network/NetworkInfoReceiver.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/network/NetworkInfoReceiver.kt
index 1af9dffd07..645329628b 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/network/NetworkInfoReceiver.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/network/NetworkInfoReceiver.kt
@@ -14,6 +14,7 @@
  * limitations under the License.
  */
 
+// This BroadcastReceiver is used only if the build code is below 24.
 @file:Suppress("DEPRECATION")
 
 package im.vector.matrix.android.internal.network
diff --git a/vector/src/main/java/im/vector/riotx/core/utils/SystemUtils.kt b/vector/src/main/java/im/vector/riotx/core/utils/SystemUtils.kt
index 39dab81b39..1905542c49 100644
--- a/vector/src/main/java/im/vector/riotx/core/utils/SystemUtils.kt
+++ b/vector/src/main/java/im/vector/riotx/core/utils/SystemUtils.kt
@@ -188,6 +188,6 @@ fun Context.toast(resId: Int) {
 }
 
 // Not in KTX anymore
-fun Context.toast(message: String) {
-    Toast.makeText(this, message, Toast.LENGTH_SHORT).show()
+fun Context.toast(message: String?) {
+    Toast.makeText(this, message ?: getString(R.string.generic_exception_error), Toast.LENGTH_SHORT).show()
 }
diff --git a/vector/src/main/java/im/vector/riotx/features/crypto/keysbackup/setup/KeysBackupSetupActivity.kt b/vector/src/main/java/im/vector/riotx/features/crypto/keysbackup/setup/KeysBackupSetupActivity.kt
index 72f6bf346d..fbc69505fa 100644
--- a/vector/src/main/java/im/vector/riotx/features/crypto/keysbackup/setup/KeysBackupSetupActivity.kt
+++ b/vector/src/main/java/im/vector/riotx/features/crypto/keysbackup/setup/KeysBackupSetupActivity.kt
@@ -153,7 +153,7 @@ class KeysBackupSetupActivity : SimpleFragmentActivity() {
                                         }
 
                                         override fun onFailure(failure: Throwable) {
-                                            failure.localizedMessage?.let { toast(it) }
+                                            toast(failure.localizedMessage ?: getString(R.string.unexpected_error))
                                             hideWaitingView()
                                         }
                                     })
diff --git a/vector/src/main/java/im/vector/riotx/features/crypto/verification/VerificationBottomSheetViewModel.kt b/vector/src/main/java/im/vector/riotx/features/crypto/verification/VerificationBottomSheetViewModel.kt
index e70211dd44..a932d0cc5f 100644
--- a/vector/src/main/java/im/vector/riotx/features/crypto/verification/VerificationBottomSheetViewModel.kt
+++ b/vector/src/main/java/im/vector/riotx/features/crypto/verification/VerificationBottomSheetViewModel.kt
@@ -46,8 +46,10 @@ import im.vector.matrix.android.api.util.MatrixItem
 import im.vector.matrix.android.api.util.toMatrixItem
 import im.vector.matrix.android.internal.crypto.crosssigning.fromBase64
 import im.vector.matrix.android.internal.crypto.crosssigning.isVerified
+import im.vector.riotx.R
 import im.vector.riotx.core.extensions.exhaustive
 import im.vector.riotx.core.platform.VectorViewModel
+import im.vector.riotx.core.resources.StringProvider
 import timber.log.Timber
 
 data class VerificationBottomSheetViewState(
@@ -71,7 +73,8 @@ class VerificationBottomSheetViewModel @AssistedInject constructor(
         @Assisted initialState: VerificationBottomSheetViewState,
         @Assisted val args: VerificationBottomSheet.VerificationArgs,
         private val session: Session,
-        private val supportedVerificationMethodsProvider: SupportedVerificationMethodsProvider)
+        private val supportedVerificationMethodsProvider: SupportedVerificationMethodsProvider,
+        private val stringProvider: StringProvider)
     : VectorViewModel<VerificationBottomSheetViewState, VerificationAction, VerificationBottomSheetViewEvents>(initialState),
         VerificationService.Listener {
 
@@ -362,9 +365,7 @@ class VerificationBottomSheetViewModel @AssistedInject constructor(
                         }
                     }
                 } catch (failure: Throwable) {
-                    failure.localizedMessage?.let {
-                        _viewEvents.post(VerificationBottomSheetViewEvents.ModalError(it))
-                    }
+                    _viewEvents.post(VerificationBottomSheetViewEvents.ModalError(failure.localizedMessage ?: stringProvider.getString(R.string.unexpected_error)))
                 }
             }
         }.exhaustive
diff --git a/vector/src/main/java/im/vector/riotx/features/home/room/detail/RoomDetailFragment.kt b/vector/src/main/java/im/vector/riotx/features/home/room/detail/RoomDetailFragment.kt
index 0ecc361d04..8c45090c91 100644
--- a/vector/src/main/java/im/vector/riotx/features/home/room/detail/RoomDetailFragment.kt
+++ b/vector/src/main/java/im/vector/riotx/features/home/room/detail/RoomDetailFragment.kt
@@ -782,7 +782,7 @@ class RoomDetailFragment @Inject constructor(
                 updateComposerText("")
             }
             is RoomDetailViewEvents.SlashCommandResultError    -> {
-                sendMessageResult.throwable.localizedMessage?.let { displayCommandError(it) }
+                displayCommandError(sendMessageResult.throwable.localizedMessage ?: getString(R.string.unexpected_error))
             }
             is RoomDetailViewEvents.SlashCommandNotImplemented -> {
                 displayCommandError(getString(R.string.not_implemented))
diff --git a/vector/src/main/java/im/vector/riotx/features/settings/VectorSettingsSecurityPrivacyFragment.kt b/vector/src/main/java/im/vector/riotx/features/settings/VectorSettingsSecurityPrivacyFragment.kt
index 91b3593cd0..d357c6ae82 100644
--- a/vector/src/main/java/im/vector/riotx/features/settings/VectorSettingsSecurityPrivacyFragment.kt
+++ b/vector/src/main/java/im/vector/riotx/features/settings/VectorSettingsSecurityPrivacyFragment.kt
@@ -332,7 +332,7 @@ class VectorSettingsSecurityPrivacyFragment @Inject constructor(
                                     }
 
                                     override fun onFailure(failure: Throwable) {
-                                        failure.localizedMessage?.let { appContext.toast(it) }
+                                        appContext.toast(failure.localizedMessage ?: getString(R.string.unexpected_error))
                                         hideLoadingView()
                                     }
                                 })
diff --git a/vector/src/main/res/values/strings_riotX.xml b/vector/src/main/res/values/strings_riotX.xml
index ccb4bfa9be..eabc7e5e0d 100644
--- a/vector/src/main/res/values/strings_riotX.xml
+++ b/vector/src/main/res/values/strings_riotX.xml
@@ -52,7 +52,7 @@
 
 
     <!-- BEGIN Strings added by Onuray -->
-
+    <string name="unexpected_error">An unexpected error occurred</string>
     <!-- END Strings added by Onuray -->