diff --git a/projects/ucap-webmessenger-ui-chat/src/lib/components/messages.component.html b/projects/ucap-webmessenger-ui-chat/src/lib/components/messages.component.html
index b77eb5ee..7df4f3e0 100644
--- a/projects/ucap-webmessenger-ui-chat/src/lib/components/messages.component.html
+++ b/projects/ucap-webmessenger-ui-chat/src/lib/components/messages.component.html
@@ -4,12 +4,13 @@
   perfectScrollbar
   fxFlexFill
   #psChatContent
+  [bufferAmount]="10"
   (psScrollUp)="onScrollup($event)"
   (psYReachStart)="onYReachStart($event)"
   (psYReachEnd)="onYReachEnd($event)"
   [enableUnequalChildrenSizes]="true"
 >
-  <div class="chat-messages" #scrollMe>
+  <div class="chat-messages" [style.opacity]="fixScreen ? 0 : 1">
     <div
       *ngIf="eventRemained && eventList.length > 0"
       class="message-row view-previous"
diff --git a/projects/ucap-webmessenger-ui-chat/src/lib/components/messages.component.ts b/projects/ucap-webmessenger-ui-chat/src/lib/components/messages.component.ts
index 95052648..e10ccebd 100644
--- a/projects/ucap-webmessenger-ui-chat/src/lib/components/messages.component.ts
+++ b/projects/ucap-webmessenger-ui-chat/src/lib/components/messages.component.ts
@@ -5,7 +5,9 @@ import {
   EventEmitter,
   Output,
   ViewChild,
-  OnDestroy
+  OnDestroy,
+  ElementRef,
+  Self
 } from '@angular/core';
 
 import {
@@ -102,7 +104,7 @@ export class MessagesComponent implements OnInit, OnDestroy {
   existNewMessage = new EventEmitter<Info<EventJson>>();
 
   @ViewChild(PerfectScrollbarDirective, { static: false })
-  psChatContent?: PerfectScrollbarDirective;
+  psChatContent: PerfectScrollbarDirective;
 
   @ViewChild(VirtualScrollerComponent, { static: false })
   private virtualScroller: VirtualScrollerComponent;
@@ -135,6 +137,7 @@ export class MessagesComponent implements OnInit, OnDestroy {
   moment = moment;
 
   existReadHere = false;
+  fixScreen = false;
 
   constructor(
     private logger: NGXLogger,
@@ -150,6 +153,13 @@ export class MessagesComponent implements OnInit, OnDestroy {
       this.loginRes = loginRes;
     });
     this.roomInfoSubscription = this.roomInfo$.subscribe(roomInfo => {
+      this.eventList = undefined;
+      this.newEventList = undefined;
+      this.searchedList = undefined;
+      this.eventInfoStatus = undefined;
+      this.eventRemained = undefined;
+      this.userInfos = undefined;
+
       this.initEventMore();
       this.roomInfo = roomInfo;
     });
@@ -305,6 +315,9 @@ export class MessagesComponent implements OnInit, OnDestroy {
       return true;
     }
     if (curIndex > 0) {
+      if (!this.eventList[curIndex]) {
+        return false;
+      }
       return (
         this.datePipe.transform(
           moment(this.eventList[curIndex].sendDate).toDate(),
@@ -435,8 +448,10 @@ export class MessagesComponent implements OnInit, OnDestroy {
 
     if (!!this.virtualScroller) {
       const e = this.eventList.find(v => v.seq === eventSeq);
-      this.virtualScroller.scrollDebounceTime = 0;
-      this.virtualScroller.scrollInto(e);
+      this.fixScreen = true;
+      this.virtualScroller.scrollInto(e, false, undefined, 0, () => {
+        this.fixScreen = false;
+      });
     }
   }