diff --git a/core/modules/link/src/Plugin/Field/FieldWidget/LinkWidget.php b/core/modules/link/src/Plugin/Field/FieldWidget/LinkWidget.php
index 56f6521..c25a7dd 100644
--- a/core/modules/link/src/Plugin/Field/FieldWidget/LinkWidget.php
+++ b/core/modules/link/src/Plugin/Field/FieldWidget/LinkWidget.php
@@ -101,7 +101,7 @@ protected static function getUriAsDisplayableString($uri) {
    */
   protected static function getUserEnteredStringAsUri($string) {
     // By default, assume the entered string is an URI.
-    $uri = $string;
+    $uri = trim($string);
 
     // Detect entity autocomplete string, map to 'entity:' URI.
     $entity_id = EntityAutocomplete::extractEntityIdFromAutocompleteInput($string);
diff --git a/core/modules/link/tests/src/Functional/LinkFieldTest.php b/core/modules/link/tests/src/Functional/LinkFieldTest.php
index f32bf3c..da7dfde 100644
--- a/core/modules/link/tests/src/Functional/LinkFieldTest.php
+++ b/core/modules/link/tests/src/Functional/LinkFieldTest.php
@@ -121,6 +121,10 @@ public function testURLValidation() {
       '/?example=llama' => '<front>?example=llama',
       '/#example' => '<front>#example',
 
+      // Trailing spaces should be ignored.
+      '/ ' => '<front>',
+      '/path with spaces ' => '/path with spaces',
+
       // @todo '<front>' is valid input for BC reasons, may be removed by
       //   https://www.drupal.org/node/2421941
       '<front>' => '&lt;front&gt;',
@@ -200,7 +204,7 @@ protected function assertValidEntries($field_name, array $valid_entries) {
       preg_match('|entity_test/manage/(\d+)|', $this->getUrl(), $match);
       $id = $match[1];
       $this->assertText(t('entity_test @id has been created.', ['@id' => $id]));
-      $this->assertRaw($string);
+      $this->assertRaw('"' . $string . '"');
     }
   }