diff --git a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/api/failure/GlobalError.kt b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/api/failure/GlobalError.kt
index b5165b6687..5b4896f95f 100644
--- a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/api/failure/GlobalError.kt
+++ b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/api/failure/GlobalError.kt
@@ -23,5 +23,10 @@ sealed class GlobalError {
     data class InvalidToken(val softLogout: Boolean) : GlobalError()
     data class ConsentNotGivenError(val consentUri: String) : GlobalError()
     data class CertificateError(val fingerprint: Fingerprint) : GlobalError()
+
+    /**
+     * The SDK requires the app (which should request the user) to perform an initial sync.
+     */
+    data class InitialSyncRequest(val reason: InitialSyncRequestReason) : GlobalError()
     object ExpiredAccount : GlobalError()
 }
diff --git a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/api/failure/InitialSyncRequestReason.kt b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/api/failure/InitialSyncRequestReason.kt
new file mode 100644
index 0000000000..5717f41f43
--- /dev/null
+++ b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/api/failure/InitialSyncRequestReason.kt
@@ -0,0 +1,27 @@
+/*
+ * Copyright (c) 2022 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.matrix.android.sdk.api.failure
+
+/**
+ * This enum provide the reason why the SDK request an initial sync to the application
+ */
+enum class InitialSyncRequestReason {
+    /**
+     * The list of ignored users has changed, and at least one user who was ignored is not ignored anymore
+     */
+    IGNORED_USERS_LIST_CHANGE,
+}
diff --git a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/api/session/Session.kt b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/api/session/Session.kt
index be924e2063..2ad0ae9e0d 100644
--- a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/api/session/Session.kt
+++ b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/api/session/Session.kt
@@ -298,6 +298,7 @@ interface Session :
          * Possible cases:
          * - The access token is not valid anymore,
          * - a M_CONSENT_NOT_GIVEN error has been received from the homeserver
+         * See [GlobalError] for all the possible cases
          */
         fun onGlobalError(session: Session, globalError: GlobalError) = Unit
     }
diff --git a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/sync/handler/UserAccountDataSyncHandler.kt b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/sync/handler/UserAccountDataSyncHandler.kt
index c7d7dce17a..ce827c2311 100644
--- a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/sync/handler/UserAccountDataSyncHandler.kt
+++ b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/sync/handler/UserAccountDataSyncHandler.kt
@@ -20,6 +20,8 @@ import com.zhuinden.monarchy.Monarchy
 import io.realm.Realm
 import io.realm.RealmList
 import io.realm.kotlin.where
+import org.matrix.android.sdk.api.failure.GlobalError
+import org.matrix.android.sdk.api.failure.InitialSyncRequestReason
 import org.matrix.android.sdk.api.pushrules.RuleScope
 import org.matrix.android.sdk.api.pushrules.RuleSetKey
 import org.matrix.android.sdk.api.pushrules.rest.GetPushRulesResponse
@@ -31,6 +33,7 @@ import org.matrix.android.sdk.api.session.room.model.RoomMemberContent
 import org.matrix.android.sdk.api.session.room.model.RoomSummary
 import org.matrix.android.sdk.api.session.sync.model.InvitedRoomSync
 import org.matrix.android.sdk.api.session.sync.model.UserAccountDataSync
+import org.matrix.android.sdk.internal.SessionManager
 import org.matrix.android.sdk.internal.database.mapper.ContentMapper
 import org.matrix.android.sdk.internal.database.mapper.PushRulesMapper
 import org.matrix.android.sdk.internal.database.mapper.asDomain
@@ -48,7 +51,10 @@ import org.matrix.android.sdk.internal.database.query.getDirectRooms
 import org.matrix.android.sdk.internal.database.query.getOrCreate
 import org.matrix.android.sdk.internal.database.query.where
 import org.matrix.android.sdk.internal.di.SessionDatabase
+import org.matrix.android.sdk.internal.di.SessionId
 import org.matrix.android.sdk.internal.di.UserId
+import org.matrix.android.sdk.internal.session.SessionListeners
+import org.matrix.android.sdk.internal.session.dispatchTo
 import org.matrix.android.sdk.internal.session.room.RoomAvatarResolver
 import org.matrix.android.sdk.internal.session.room.membership.RoomDisplayNameResolver
 import org.matrix.android.sdk.internal.session.room.membership.RoomMemberHelper
@@ -67,7 +73,10 @@ internal class UserAccountDataSyncHandler @Inject constructor(
         private val directChatsHelper: DirectChatsHelper,
         private val updateUserAccountDataTask: UpdateUserAccountDataTask,
         private val roomAvatarResolver: RoomAvatarResolver,
-        private val roomDisplayNameResolver: RoomDisplayNameResolver
+        private val roomDisplayNameResolver: RoomDisplayNameResolver,
+        @SessionId private val sessionId: String,
+        private val sessionManager: SessionManager,
+        private val sessionListeners: SessionListeners
 ) {
 
     fun handle(realm: Realm, accountData: UserAccountDataSync?) {
@@ -186,9 +195,10 @@ internal class UserAccountDataSyncHandler @Inject constructor(
 
     private fun handleIgnoredUsers(realm: Realm, event: UserAccountDataEvent) {
         val userIds = event.content.toModel<IgnoredUsersContent>()?.ignoredUsers?.keys ?: return
-        realm.where(IgnoredUserEntity::class.java)
-                .findAll()
-                .deleteAllFromRealm()
+        val currentIgnoredUsers = realm.where(IgnoredUserEntity::class.java).findAll()
+        val currentIgnoredUserIds = currentIgnoredUsers.map { it.userId }
+        // Delete the previous list
+        currentIgnoredUsers.deleteAllFromRealm()
         // And save the new received list
         userIds.forEach { realm.createObject(IgnoredUserEntity::class.java).apply { userId = it } }
 
@@ -204,6 +214,20 @@ internal class UserAccountDataSyncHandler @Inject constructor(
                 .forEach {
                     it.deleteOnCascade(true)
                 }
+
+        // Handle the case when some users are unignored from another session
+        val mustRefreshCache = currentIgnoredUserIds.any { currentIgnoredUserId -> currentIgnoredUserId !in userIds }
+        if (mustRefreshCache) {
+            Timber.d("A user has been unignored from another session, an initial sync should be performed")
+            dispatchMustRefresh()
+        }
+    }
+
+    private fun dispatchMustRefresh() {
+        val session = sessionManager.getSessionComponent(sessionId)?.session()
+        session.dispatchTo(sessionListeners) { safeSession, listener ->
+            listener.onGlobalError(safeSession, GlobalError.InitialSyncRequest(InitialSyncRequestReason.IGNORED_USERS_LIST_CHANGE))
+        }
     }
 
     private fun handleBreadcrumbs(realm: Realm, event: UserAccountDataEvent) {
diff --git a/vector/src/main/java/im/vector/app/core/platform/VectorBaseActivity.kt b/vector/src/main/java/im/vector/app/core/platform/VectorBaseActivity.kt
index 4796022856..febcfc5ef2 100644
--- a/vector/src/main/java/im/vector/app/core/platform/VectorBaseActivity.kt
+++ b/vector/src/main/java/im/vector/app/core/platform/VectorBaseActivity.kt
@@ -46,6 +46,7 @@ import androidx.viewbinding.ViewBinding
 import com.airbnb.mvrx.MavericksView
 import com.bumptech.glide.util.Util
 import com.google.android.material.appbar.MaterialToolbar
+import com.google.android.material.dialog.MaterialAlertDialogBuilder
 import com.google.android.material.snackbar.Snackbar
 import dagger.hilt.android.EntryPointAccessors
 import im.vector.app.BuildConfig
@@ -86,6 +87,7 @@ import kotlinx.coroutines.flow.launchIn
 import kotlinx.coroutines.flow.onEach
 import org.matrix.android.sdk.api.extensions.tryOrNull
 import org.matrix.android.sdk.api.failure.GlobalError
+import org.matrix.android.sdk.api.failure.InitialSyncRequestReason
 import reactivecircus.flowbinding.android.view.clicks
 import timber.log.Timber
 import javax.inject.Inject
@@ -266,9 +268,27 @@ abstract class VectorBaseActivity<VB : ViewBinding> : AppCompatActivity(), Maver
             is GlobalError.CertificateError     ->
                 handleCertificateError(globalError)
             GlobalError.ExpiredAccount          -> Unit // TODO Handle account expiration
+            is GlobalError.InitialSyncRequest   -> handleInitialSyncRequest(globalError)
         }
     }
 
+    private fun handleInitialSyncRequest(initialSyncRequest: GlobalError.InitialSyncRequest) {
+        MaterialAlertDialogBuilder(this)
+                .setTitle(R.string.initial_sync_request_title)
+                .setMessage(
+                        getString(R.string.initial_sync_request_content, getString(
+                                when (initialSyncRequest.reason) {
+                                    InitialSyncRequestReason.IGNORED_USERS_LIST_CHANGE -> R.string.initial_sync_request_reason_unignored_users
+                                }
+                        ))
+                )
+                .setPositiveButton(R.string.ok) { _, _ ->
+                    MainActivity.restartApp(this, MainActivityArgs(clearCache = true))
+                }
+                .setNegativeButton(R.string.later, null)
+                .show()
+    }
+
     private fun handleCertificateError(certificateError: GlobalError.CertificateError) {
         singletonEntryPoint()
                 .unrecognizedCertificateDialog()
diff --git a/vector/src/main/res/values/strings.xml b/vector/src/main/res/values/strings.xml
index ffd4333071..89ed125afd 100644
--- a/vector/src/main/res/values/strings.xml
+++ b/vector/src/main/res/values/strings.xml
@@ -176,6 +176,9 @@
     <string name="initial_sync_start_importing_account_groups">Initial sync:\nImporting communities</string>
     <string name="initial_sync_start_importing_account_data">Initial sync:\nImporting account data</string>
 
+    <string name="initial_sync_request_title">Initial sync request</string>
+    <string name="initial_sync_request_content">${app_name} needs to perform a clear cache to be up to date, for the following reason:\n%s\n\nNote that this action will restart the app and it may take some time.</string>
+    <string name="initial_sync_request_reason_unignored_users">- Some users have been unignored</string>
 
     <string name="event_status_sent_message">Message sent</string>
     <string name="event_status_sending_message">Sending message…</string>