diff --git a/.changeset/metal-seals-swim.md b/.changeset/metal-seals-swim.md
new file mode 100644
index 00000000..bb5d92dd
--- /dev/null
+++ b/.changeset/metal-seals-swim.md
@@ -0,0 +1,5 @@
+---
+"@0no-co/graphqlsp": patch
+---
+
+Fix wrong fileType diagnostic error when introspection is disabled
diff --git a/packages/graphqlsp/src/graphql/getSchema.ts b/packages/graphqlsp/src/graphql/getSchema.ts
index ba9d89c5..a45007b4 100644
--- a/packages/graphqlsp/src/graphql/getSchema.ts
+++ b/packages/graphqlsp/src/graphql/getSchema.ts
@@ -126,12 +126,14 @@ export const loadSchema = (
     }
 
     if (ref.current) {
-      saveTadaIntrospection(
-        ref.current.introspection,
-        tadaOutputLocation,
-        tadaDisablePreprocessing,
-        logger
-      );
+      if (ref.current && ref.current.tadaOutputLocation !== undefined) {
+        saveTadaIntrospection(
+          ref.current.introspection,
+          tadaOutputLocation,
+          tadaDisablePreprocessing,
+          logger
+        );
+      }
     } else if (ref.multi) {
       Object.values(ref.multi).forEach(value => {
         if (!value) return;