diff --git a/pkg/analyzer/lib/src/summary2/linked_element_factory.dart b/pkg/analyzer/lib/src/summary2/linked_element_factory.dart
index 4980cdb..aed4049 100644
--- a/pkg/analyzer/lib/src/summary2/linked_element_factory.dart
+++ b/pkg/analyzer/lib/src/summary2/linked_element_factory.dart
@@ -113,7 +113,13 @@
 
     var reader = _libraryReaders[uri];
     if (reader == null) {
-      final rootChildren = rootReference.children.map((e) => e.name).toList();
+      var rootChildren = rootReference.children.map((e) => e.name).toList();
+      if (rootChildren.length > 100) {
+        rootChildren = [
+          ...rootChildren.take(100),
+          '... (${rootChildren.length} total)'
+        ];
+      }
       throw ArgumentError(
         'Missing library: $uri\n'
         'Libraries: $uriListWithLibraryElements\n'