diff --git a/frontend/src/app/main/errors.cljs b/frontend/src/app/main/errors.cljs
index 5cc437e4a3..223e916261 100644
--- a/frontend/src/app/main/errors.cljs
+++ b/frontend/src/app/main/errors.cljs
@@ -43,16 +43,33 @@
 
 (defn stale-asset-error?
   "Returns true if the error matches the signature of a cross-build
-  module mismatch: accessing a ClojureScript keyword constant that
-  doesn't exist on the shared $APP object."
+  module mismatch. Two distinct patterns can appear depending on which
+  cross-module reference is accessed first:
+
+  1. Keyword constants  – names contain '$cljs$cst$'; these arise when a
+     compiled keyword defined in shared.js is absent in the version of
+     shared.js already resident in the browser.
+
+  2. Protocol dispatch – names contain '$cljs$core$I'; these arise when
+     main-workspace.js (new build) tries to invoke a protocol method on
+     an object whose prototype was stamped by an older shared.js that
+     used different mangled property names (e.g. the LazySeq /
+     instaparse crash: 'Cannot read properties of undefined (reading
+     \\'$cljs$core$IFn$_invoke$arity$1$\\')').
+
+  Both patterns are symptoms of the same split-brain deployment
+  scenario (browser has JS chunks from two different builds) and
+  should trigger a hard page reload."
   [cause]
   (when (some? cause)
     (let [message (ex-message cause)]
       (and (string? message)
-           (str/includes? message "$cljs$cst$")
+           (or (str/includes? message "$cljs$cst$")
+               (str/includes? message "$cljs$core$I"))
            (or (str/includes? message "is undefined")
                (str/includes? message "is null")
-               (str/includes? message "is not a function"))))))
+               (str/includes? message "is not a function")
+               (str/includes? message "Cannot read properties of undefined"))))))
 
 (defn exception->error-data
   [cause]