diff --git a/www/common/outer/cache-store.js b/www/common/outer/cache-store.js
index 7a0a50209..a7b1bd3d7 100644
--- a/www/common/outer/cache-store.js
+++ b/www/common/outer/cache-store.js
@@ -32,7 +32,7 @@ define([
             if (!allowed) { return void cb('NOCACHE'); }
             cache.getItem(id, function (err, obj) {
                 if (err || !obj || !obj.c) {
-                    return void cb(err || 'EINVAL');
+                    return void cb(Util.serializeError(err || 'EINVAL'));
                 }
                 cb(null, obj.c);
                 obj.t = +new Date();
@@ -50,7 +50,7 @@ define([
                 c: u8,
                 t: (+new Date()) // 't' represent the "lastAccess" of this cache (get or set)
             }, function (err) {
-                cb(err);
+                cb(Util.serializeError(err));
             });
         });
     };
@@ -64,7 +64,7 @@ define([
             if (!allowed) { return void cb('NOCACHE'); }
             cache.getItem(id, function (err, obj) {
                 if (err || !obj || !Array.isArray(obj.c)) {
-                    return void cb(err || 'EINVAL');
+                    return void cb(Util.serializeError(err || 'EINVAL'));
                 }
                 cb(null, obj);
                 obj.t = +new Date();
@@ -108,7 +108,7 @@ define([
                     c: val,
                     t: (+new Date()) // 't' represent the "lastAccess" of this cache (get or set)
                 }, function (err) {
-                    if (err) { onError(err); }
+                    if (err) { onError(Util.serializeError(err)); }
                 });
 
             }, 50);
diff --git a/www/common/sframe-common-outer.js b/www/common/sframe-common-outer.js
index ca760efb8..15c192d16 100644
--- a/www/common/sframe-common-outer.js
+++ b/www/common/sframe-common-outer.js
@@ -157,7 +157,24 @@ define([
                 var msgEv = _Util.mkEvent();
                 var iframe = $('#sbox-iframe')[0].contentWindow;
                 var postMsg = function (data) {
-                    iframe.postMessage(data, '*');
+                    try {
+                        iframe.postMessage(data, '*');
+                    } catch (err) {
+                        console.error(err);
+                        console.error(data);
+                        if (data && data.error && data.error instanceof Error) {
+                            data.error = Util.serializeError(data.error);
+                            try {
+                                iframe.postMessage(data, '*');
+                            } catch (err2) {
+                                // XXX
+                                console.error("impossible serialization");
+                                throw err2;
+                            }
+                        } else {
+                             throw err;
+                        }
+                    }
                 };
                 var whenReady = waitFor(function (msg) {
                     if (msg.source !== iframe) { return; }