diff --git a/packages/hydrooj/src/handler/discussion.ts b/packages/hydrooj/src/handler/discussion.ts
index 32658249f..ebaba2b9a 100644
--- a/packages/hydrooj/src/handler/discussion.ts
+++ b/packages/hydrooj/src/handler/discussion.ts
@@ -56,7 +56,9 @@ class DiscussionHandler extends Handler {
         // TODO(twd2): exclude problem/contest discussions?
         // TODO(iceboy): continuation based pagination.
         this.vnode = await discussion.getVnode(domainId, typeMapper[type], name, this.user._id);
-        if (!discussion.checkVNodeVisibility(typeMapper[type], this.vnode, this.user)) throw new DiscussionNodeNotFoundError(this.vnode.id);
+        if (!discussion.checkVNodeVisibility(typeMapper[type], this.vnode, this.user)) {
+            throw new DiscussionNodeNotFoundError(domainId, this.vnode.id);
+        }
         if (this.ddoc) {
             this.ddoc.parentType ||= this.vnode.type;
             this.ddoc.parentId ||= this.vnode.id;
@@ -422,7 +424,7 @@ class DiscussionEditHandler extends DiscussionHandler {
 }
 
 export async function apply(ctx) {
-    ctx.Route('discussion_main', '/discuss', DiscussionMainHandler);
+    ctx.Route('discussion_main', '/discuss', DiscussionMainHandler, PERM.PERM_VIEW_DISCUSSION);
     ctx.Route('discussion_detail', '/discuss/:did', DiscussionDetailHandler);
     ctx.Route('discussion_edit', '/discuss/:did/edit', DiscussionEditHandler);
     ctx.Route('discussion_raw', '/discuss/:did/raw', DiscussionRawHandler);
diff --git a/packages/hydrooj/src/model/discussion.ts b/packages/hydrooj/src/model/discussion.ts
index df201cea5..8e2221f06 100644
--- a/packages/hydrooj/src/model/discussion.ts
+++ b/packages/hydrooj/src/model/discussion.ts
@@ -276,15 +276,16 @@ export function flushNodes(domainId: string) {
 export async function getVnode(domainId: string, type: number, id: string, uid?: number) {
     if (type === document.TYPE_PROBLEM) {
         const pdoc = await problem.get(domainId, Number.isSafeInteger(+id) ? +id : id, problem.PROJECTION_LIST);
-        if (!pdoc) throw new DiscussionNodeNotFoundError(`problem/${id}`);
+        if (!pdoc) throw new DiscussionNodeNotFoundError(domainId, `problem/${id}`);
         return { ...pdoc, type, id: pdoc.docId };
     }
     if ([document.TYPE_CONTEST, document.TYPE_TRAINING].includes(type as any)) {
         const model = type === document.TYPE_TRAINING ? training : contest;
-        if (!ObjectId.isValid(id)) throw new DiscussionNodeNotFoundError(`contest/${id}`);
+        const typeName = type === document.TYPE_TRAINING ? 'training' : 'contest';
+        if (!ObjectId.isValid(id)) throw new DiscussionNodeNotFoundError(domainId, `${typeName}/${id}`);
         const _id = new ObjectId(id);
         const tdoc = await model.get(domainId, _id);
-        if (!tdoc) throw new DiscussionNodeNotFoundError(`contest/${id}`);
+        if (!tdoc) throw new DiscussionNodeNotFoundError(domainId, `${typeName}/${id}`);
         if (uid) {
             const tsdoc = await model.getStatus(domainId, _id, uid);
             tdoc.attend = tsdoc?.attend || tsdoc?.enroll;