diff --git a/packages/hydrooj/package.json b/packages/hydrooj/package.json
index 3ed5aa878..ab04e8b7a 100644
--- a/packages/hydrooj/package.json
+++ b/packages/hydrooj/package.json
@@ -1,6 +1,6 @@
 {
     "name": "hydrooj",
-    "version": "3.1.21",
+    "version": "3.1.22",
     "bin": "bin/hydrooj.js",
     "main": "src/loader",
     "module": "src/loader",
diff --git a/packages/hydrooj/src/service/bus.ts b/packages/hydrooj/src/service/bus.ts
index 3bdeb1d97..fbe31290b 100644
--- a/packages/hydrooj/src/service/bus.ts
+++ b/packages/hydrooj/src/service/bus.ts
@@ -64,9 +64,14 @@ export interface EventMap extends Record<string, any> {
     'handler/create': (thisArg: Handler) => VoidReturn
     'handler/init': (thisArg: Handler) => VoidReturn
     'handler/before-prepare/UserRegister': (thisArg: UserRegisterHandler) => VoidReturn
+    'handler/before-prepare': (thisArg: Handler) => VoidReturn
     'handler/before/UserRegister': (thisArg: UserRegisterHandler) => VoidReturn
+    'handler/before': (thisArg: Handler) => VoidReturn
     'handler/after/UserRegister': (thisArg: UserRegisterHandler) => VoidReturn
+    'handler/after': (thisArg: Handler) => VoidReturn
     'handler/finish/UserRegister': (thisArg: UserRegisterHandler) => VoidReturn
+    'handler/finish': (thisArg: Handler) => VoidReturn
+    'handler/error': (thisArg: Handler) => VoidReturn
     'handler/solution/get': (thisArg: ProblemSolutionHandler) => VoidReturn
 
     'discussion/before-add': (payload: Partial<DiscussionDoc>) => VoidReturn
diff --git a/packages/hydrooj/src/service/server.ts b/packages/hydrooj/src/service/server.ts
index 7ce15f561..b85a91240 100644
--- a/packages/hydrooj/src/service/server.ts
+++ b/packages/hydrooj/src/service/server.ts
@@ -725,6 +725,8 @@ async function handle(ctx, HandlerClass, checker) {
         await bail('handler/finish', h);
     } catch (e) {
         try {
+            await bail(`handler/error/${HandlerClass.name.replace(/Handler$/, '')}`, h);
+            await bail('handler/error', h);
             await h.onerror(e);
         } catch (err) {
             h.response.code = 500;
diff --git a/packages/ui-default/handler.ts b/packages/ui-default/handler.ts
index 613b8db1d..761cf2970 100644
--- a/packages/ui-default/handler.ts
+++ b/packages/ui-default/handler.ts
@@ -76,14 +76,16 @@ async function constant(args: ConstantArgs) {
   return version;
 }
 
-bus.on('handler/after', async (that) => {
-  if (that.response.template) {
+const versionHandler = async (that) => {
+  if (that.response.template && !that.UiContext.constantVersion) {
     that.UiContext.constantVersion = await constant({
       domainId: that.domainId,
       lang: that.session.viewLang || that.user.viewLang,
     });
   }
-});
+};
+bus.on('handler/after', versionHandler);
+bus.on('handler/error', versionHandler);
 
 class WikiHelpHandler extends Handler {
   noCheckPermView = true;
diff --git a/packages/ui-default/package.json b/packages/ui-default/package.json
index c930f2baf..0ced522f3 100644
--- a/packages/ui-default/package.json
+++ b/packages/ui-default/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@hydrooj/ui-default",
-  "version": "4.26.10",
+  "version": "4.26.11",
   "author": "undefined <i@undefined.moe>",
   "license": "AGPL-3.0",
   "main": "hydro.js",