diff --git a/build/jsroot.js b/build/jsroot.js
index 13e581f6c..deb284ff2 100644
--- a/build/jsroot.js
+++ b/build/jsroot.js
@@ -121992,9 +121992,9 @@ class WebWindowHandle {
    constructor(socket_kind, credits) {
       this.kind = socket_kind;
       this.state = 0;
-      this.credits = credits || 10;
+      this.credits = Math.max(3, credits || 10);
       this.cansend = this.credits;
-      this.ackn = this.credits;
+      this.ackn = this.credits; // this number will be send to server with first message
       this.send_seq = 1; // sequence counter of send messages
       this.recv_seq = 0; // sequence counter of received messages
    }
@@ -122426,6 +122426,7 @@ class WebWindowHandle {
                   this.invokeReceiver(true, 'onWebsocketClosed');
                } else if (msg.indexOf('NEW_KEY=') === 0) {
                   this.new_key = msg.slice(8);
+                  console.log('get new key', this.new_key);
                   this.storeKeyInUrl();
                   if (this._ask_reload)
                      this.askReload(true);
@@ -122438,7 +122439,7 @@ class WebWindowHandle {
             else
                this.provideData(chid, msg);
 
-            if (this.ackn > 7)
+            if (this.ackn > Math.max(2, this.credits*0.7))
                this.send('READY', 0); // send dummy message to server
          };
 
@@ -122508,11 +122509,9 @@ class WebWindowHandle {
    /** @summary Replace widget URL with new key
      * @private */
    storeKeyInUrl() {
-      if (!this._handling_reload)
-         return;
-
       let href = (typeof document !== 'undefined') ? document.URL : null;
-      if (isStr(href) && (typeof window !== 'undefined') && window?.history) {
+
+      if (this._can_modify_url && isStr(href) && (typeof window !== 'undefined')) {
          let prefix = '&key=', p = href.indexOf(prefix);
          if (p < 0) {
             prefix = '?key=';
@@ -122522,9 +122521,10 @@ class WebWindowHandle {
             const p1 = href.indexOf('#', p+1), p2 = href.indexOf('&', p+1),
                   pp = (p1 < 0) ? p2 : (p2 < 0 ? p1 : Math.min(p1, p2));
             href = href.slice(0, p) + prefix + this.new_key + (pp < 0 ? '' : href.slice(pp));
-            window.history.replaceState(window.history.state, undefined, href);
+            window.history?.replaceState(window.history.state, undefined, href);
          }
       }
+
       if (typeof sessionStorage !== 'undefined') {
          sessionStorage.setItem('RWebWindow_SessionKey', sessionKey);
          sessionStorage.setItem('RWebWindow_Key', this.new_key);