diff --git a/server/app/pending_changes.py b/server/app/pending_changes.py
index 96ebdcd..8150398 100644
--- a/server/app/pending_changes.py
+++ b/server/app/pending_changes.py
@@ -102,7 +102,9 @@
                 target.unlink(missing_ok=True)
             else:
                 target.write_text(previous_content, encoding="utf-8")
-            raise PendingChangeError("Applied change failed validation and was rolled back")
+            issues = validation.get("issues", [])
+            details = "\n".join(f"  - {i['path']} ({i['code']}): {i['message']}" for i in issues[:10])
+            raise PendingChangeError(f"Applied change failed validation and was rolled back. Issues:\n{details}")
 
         now = datetime.now(UTC).replace(microsecond=0).isoformat().replace("+00:00", "Z")
         change["status"] = "applied"
@@ -143,7 +145,9 @@
         validation = validate_repository(self.settings)
         if validation["status"] != "ok":
             target.write_text(previous_content, encoding="utf-8")
-            raise PendingChangeError("Applied change failed validation and was rolled back")
+            issues = validation.get("issues", [])
+            details = "\n".join(f"  - {i['path']} ({i['code']}): {i['message']}" for i in issues[:10])
+            raise PendingChangeError(f"Applied change failed validation and was rolled back. Issues:\n{details}")
 
         now = datetime.now(UTC).replace(microsecond=0).isoformat().replace("+00:00", "Z")
         change["status"] = "applied"