diff --git a/dashboard/src/components/BackupDialog.vue b/dashboard/src/components/BackupDialog.vue
index 88deb7aa3..7b12a5764 100644
--- a/dashboard/src/components/BackupDialog.vue
+++ b/dashboard/src/components/BackupDialog.vue
@@ -18,6 +18,7 @@ const formError = ref({});
 const busy = ref(false);
 const provider = ref('');
 const oldProvider = ref('');
+const oldFormat = ref('');
 const providerConfig = ref({
   limits: {},
   mountOptions: {},
@@ -161,6 +162,7 @@ defineExpose({
     oldProvider.value = result.provider;
     provider.value = result.provider;
     providerConfig.value = result;
+    oldFormat.value = result.format;
 
     // ensure we have all required child objects
     if (!providerConfig.value.mountOptions) providerConfig.value.mountOptions = {};
@@ -197,7 +199,7 @@ defineExpose({
         <fieldset :disabled="busy">
           <input style="display: none;" type="submit"/>
           <div class="error-label" v-show="formError.generic">{{ formError.generic }}</div>
-          <div class="warning-label" v-show="oldProvider !== provider">Backups in the old storage location have to be removed manually.</div>
+          <div class="warning-label" v-show="oldProvider !== provider || oldFormat !== providerConfig.format">{{ $t('backups.configureBackupStorage.formatChangeNote') }}</div>
 
           <BackupProviderForm v-model:provider="provider" v-model:provider-config="providerConfig" :form-error="formError"/>
 
diff --git a/dashboard/src/components/BackupProviderForm.vue b/dashboard/src/components/BackupProviderForm.vue
index 5acfc55c6..495e72ab5 100644
--- a/dashboard/src/components/BackupProviderForm.vue
+++ b/dashboard/src/components/BackupProviderForm.vue
@@ -277,7 +277,6 @@ onMounted(async () => {
     <FormGroup v-if="provider !== 'noop'">
       <label for="formatInput">{{ $t('backups.configureBackupStorage.format') }} <sup><a href="https://docs.cloudron.io/backups/#backup-formats" class="help" target="_blank"><i class="fa fa-question-circle"></i></a></sup></label>
       <SingleSelect id="formatInput" v-model="providerConfig.format" :options="BACKUP_FORMATS" option-label="name" option-key="value" required />
-      <!-- TODO old config format not known <div class="warning-label" v-show="format !== config.format">{{ $t('backups.configureBackupStorage.formatChangeNote') }}</div> -->
       <div class="warning-label" v-show="providerConfig.format === 'rsync' && (s3like(provider) || provider === 'gcs')">{{ $t('backups.configureBackupStorage.s3LikeNote') }} <sup><a href="https://docs.cloudron.io/backups/#amazon-s3" class="help" target="_blank"><i class="fa fa-question-circle"></i></a></sup></div>
     </FormGroup>