some of these urls are necessary as strings

modules/islandora_iiif/src/Plugin/views/style/IIIFManifest.php

@@ -186,7 +186,7 @@ class IIIFManifest extends StylePluginBase {
         foreach ($images as $image) {
           // Create the IIIF URL for this file
           // Visiting $iiif_url will resolve to the info.json for the image.
-          $file_url = $image->entity->toUrl();
+          $file_url = $image->entity->toUrl()->toString();
           $mime_type = $image->entity->getMimeType();
           $iiif_url = rtrim($iiif_address, '/') . '/' . urlencode($file_url);
 

src/Form/IslandoraSettingsForm.php

@@ -7,6 +7,7 @@ use Drupal\Core\Entity\EntityTypeBundleInfoInterface;
 use Drupal\Core\Form\ConfigFormBase;
 use Drupal\Core\Form\FormStateInterface;
 use Drupal\Core\Site\Settings;
+use Drupal\Core\Url;
 use GuzzleHttp\Exception\ConnectException;
 use Islandora\Crayfish\Commons\Client\GeminiClient;
 use Stomp\Client;
@@ -271,6 +272,7 @@ class IslandoraSettingsForm extends ConfigFormBase {
     $geminiUrlValue = trim($form_state->getValue(self::GEMINI_URL));
     if (!empty($geminiUrlValue)) {
       try {
+        $geminiUrl = Url::fromUri($geminiUrlValue);
         $client = GeminiClient::create($geminiUrlValue, $this->logger('islandora'));
         $client->findByUri('http://example.org');
       }

tests/src/Functional/JsonldSelfReferenceReactionTest.php

@@ -153,7 +153,7 @@ class JsonldSelfReferenceReactionTest extends IslandoraFunctionalTestBase {
     $reaction_id = 'islandora_map_uri_predicate';
 
     list($file, $media) = $this->makeMediaAndFile($account);
-    $media_url = $media->toUrl('canonical', ['absolute' => TRUE]);
+    $media_url = $media->toUrl('canonical', ['absolute' => TRUE])->toString();
     $file_url = $file->createFileUrl(FALSE);
 
     $this->drupalGet($media_url);