diff -u b/modules/demo/src/Tests/TMGMTDemoTest.php b/modules/demo/src/Tests/TMGMTDemoTest.php
--- b/modules/demo/src/Tests/TMGMTDemoTest.php
+++ b/modules/demo/src/Tests/TMGMTDemoTest.php
@@ -50,7 +50,7 @@
     $this->clickLink(t('Translate'));
     $this->drupalPostForm(NULL, $edit, t('Request translation'));
     $this->assertText(t('2 jobs need to be checked out.'));
-    // Check to see if no items selected and the error message pops on sources.
+    // Check to see if no items are selected and the error message pops up.
     $this->drupalPostForm('admin/tmgmt/sources', array(), t('Request translation'));
     $this->assertUniqueText(t("You didn't select any source objects"));
   }
diff -u b/src/Form/SourceOverviewForm.php b/src/Form/SourceOverviewForm.php
--- b/src/Form/SourceOverviewForm.php
+++ b/src/Form/SourceOverviewForm.php
@@ -153,10 +153,15 @@
    * {@inheritdoc}
    */
   public function validateForm(array &$form, FormStateInterface $form_state) {
-    if (!$form_state->getValue('values')) {
+    $items = &$form['items']['#value'];
+    $issearch = FALSE;
+    if ($_POST['op'] == t('Search')) {
+      $issearch = TRUE;
+    }
+    if (empty($items) && !$issearch) {
       $form_state->setError($form, t("You didn't select any source objects"));
     }
-    $plugin =  $form_state->get('plugin');
+    $plugin = $form_state->get('plugin');
     $item_type = $form_state->get('item_type');
     // Execute the validation method on the source plugin controller.
     $source_ui = $this->sourceManager->createUIInstance($plugin);