src/Routing/Routes.php | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/src/Routing/Routes.php b/src/Routing/Routes.php
index f38af6e..5286512 100644
--- a/src/Routing/Routes.php
+++ b/src/Routing/Routes.php
@@ -217,6 +217,15 @@ class Routes implements ContainerInjectionInterface {
       return $routes;
     }
 
+    // File upload routes are only necessary for resource types that have file
+    // fields.
+    $has_file_field = array_reduce($resource_type->getRelatableResourceTypes(), function ($carry, array $target_resource_types) {
+      return $carry || static::hasNonInternalFileTargetResourceTypes($target_resource_types);
+    }, FALSE);
+    if (!$has_file_field) {
+      return $routes;
+    }
+
     if ($resource_type->isMutable()) {
       $path = $resource_type->getPath();
       $entity_type_id = $resource_type->getEntityTypeId();
@@ -434,6 +443,22 @@ class Routes implements ContainerInjectionInterface {
   }
 
   /**
+   * Determines if an array of resource types lists non-internal "file" ones.
+   *
+   * @param \Drupal\jsonapi\ResourceType\ResourceType[] $resource_types
+   *   The resource types to check.
+   *
+   * @return bool
+   *   TRUE if there is at least one non-internal "file" resource type in the
+   *   given array; FALSE otherwise.
+   */
+  protected static function hasNonInternalFileTargetResourceTypes(array $resource_types) {
+    return array_reduce($resource_types, function ($carry, ResourceType $target) {
+      return $carry || (!$target->isInternal() && $target->getEntityTypeId() === 'file');
+    }, FALSE);
+  }
+
+  /**
    * Gets the resource type from a route or request's parameters.
    *
    * @param array $parameters