diff --git a/.changeset/pretty-mails-switch.md b/.changeset/pretty-mails-switch.md
new file mode 100644
index 00000000..2f0d3d5c
--- /dev/null
+++ b/.changeset/pretty-mails-switch.md
@@ -0,0 +1,5 @@
+---
+"@farfetched/core": minor
+---
+
+Runtime deprecation warning in `attachOperation`
diff --git a/packages/core/src/attach/attach.ts b/packages/core/src/attach/attach.ts
index 9877abc8..09120638 100644
--- a/packages/core/src/attach/attach.ts
+++ b/packages/core/src/attach/attach.ts
@@ -106,6 +106,10 @@ export function attachOperation<
     mapParams?: (params: NewParams, source?: any) => OriginalParams;
   }
 ) {
+  console.error(
+    'attachOperation is deprecated since 0.12, please read the migration guide: https://farfetched.pages.dev/adr/attach_operation_deprecation.html'
+  );
+
   const { source, mapParams } = config ?? {};
 
   return operation.__.experimentalAPI?.attach({