diff --git a/packages/hydrooj/src/handler/homework.ts b/packages/hydrooj/src/handler/homework.ts
index 95a5c96f7..22fa78ee1 100644
--- a/packages/hydrooj/src/handler/homework.ts
+++ b/packages/hydrooj/src/handler/homework.ts
@@ -20,8 +20,15 @@ import {
 } from '../service/server';
 import { ContestCodeHandler, ContestFileDownloadHandler, ContestScoreboardHandler } from './contest';
 
-const validatePenaltyRules = (input: string) => yaml.load(input);
-const convertPenaltyRules = validatePenaltyRules;
+const validatePenaltyRules = (input: string) => {
+    try {
+        yaml.load(input);
+        return true;
+    } catch (e) {
+        return false;
+    }
+};
+const convertPenaltyRules = (input: string) => yaml.load(input);
 
 class HomeworkMainHandler extends Handler {
     @param('group', Types.Name, true)
diff --git a/packages/hydrooj/src/model/problem.ts b/packages/hydrooj/src/model/problem.ts
index 5673701f5..ce91df227 100644
--- a/packages/hydrooj/src/model/problem.ts
+++ b/packages/hydrooj/src/model/problem.ts
@@ -145,6 +145,7 @@ export class ProblemModel {
         tag: string[] = [], meta: ProblemCreateOptions = {},
     ) {
         const [doc] = await ProblemModel.getMulti(domainId, {})
+            .withReadPreference('primary')
             .sort({ docId: -1 }).limit(1).project({ docId: 1 })
             .toArray();
         const result = await ProblemModel.addWithId(
diff --git a/packages/hydrooj/src/upgrade.ts b/packages/hydrooj/src/upgrade.ts
index 0fb5df59c..3b7a40ead 100644
--- a/packages/hydrooj/src/upgrade.ts
+++ b/packages/hydrooj/src/upgrade.ts
@@ -550,6 +550,9 @@ export const coreScripts: MigrationScript[] = [
             }
         }
         await iterateAllProblem(['domainId', 'docId', 'tag'], async (pdoc) => {
+            if (pdoc.tag && ['string', 'number'].includes(typeof pdoc.tag)) {
+                return { tag: [pdoc.tag.toString().trim()].filter((i) => i) };
+            }
             if (pdoc.tag?.some((i) => typeof i !== 'string')) {
                 return { tag: pdoc.tag.filter((i) => i).map((i) => i.toString()) };
             }