diff --git a/runtime/src/js/pgadmin.js b/runtime/src/js/pgadmin.js
index 68f26b43e23..5f2daf578b3 100644
--- a/runtime/src/js/pgadmin.js
+++ b/runtime/src/js/pgadmin.js
@@ -38,9 +38,22 @@ let docsURLSubStrings = ['www.enterprisedb.com', 'www.postgresql.org', 'www.pgad
 process.env['ELECTRON_ENABLE_SECURITY_WARNINGS'] = false;
 
 // Paths to the rest of the app
-
 let [pythonPath, pgadminFile] = misc.getAppPaths(__dirname);
 
+// Do not allow a second instance of pgAdmin to run.
+const gotTheLock = app.requestSingleInstanceLock();
+if (!gotTheLock) {
+  app.quit();
+} else {
+  app.on('second-instance', () => {
+    // Someone tried to run a second instance, we should focus our window.
+    if (pgAdminMainScreen) {
+      if (pgAdminMainScreen.isMinimized()) pgAdminMainScreen.restore();
+      pgAdminMainScreen.focus();
+    }
+  });
+}
+
 // Override the paths above, if a developer needs to
 if (fs.existsSync('dev_config.json')) {
   try {
diff --git a/web/pgadmin/static/js/custom_hooks.js b/web/pgadmin/static/js/custom_hooks.js
index 085660d57b7..ac80abb1140 100644
--- a/web/pgadmin/static/js/custom_hooks.js
+++ b/web/pgadmin/static/js/custom_hooks.js
@@ -211,7 +211,7 @@ export function useForceUpdate() {
   return React.useReducer(() => ({}), {})[1];
 }
 
-export function useBeforeUnload({enabled, isNewTab, beforeClose, closePanel }) {
+export function useBeforeUnload({ enabled, isNewTab, beforeClose, closePanel }) {
   const onBeforeUnload = useCallback((e)=>{
     e.preventDefault();
     e.returnValue = 'prevent';
diff --git a/web/pgadmin/tools/erd/static/js/erd_tool/components/BeforeUnload.jsx b/web/pgadmin/tools/erd/static/js/erd_tool/components/BeforeUnload.jsx
index 0fd2f4e9faa..ac3eb65f4e4 100644
--- a/web/pgadmin/tools/erd/static/js/erd_tool/components/BeforeUnload.jsx
+++ b/web/pgadmin/tools/erd/static/js/erd_tool/components/BeforeUnload.jsx
@@ -1,19 +1,23 @@
-import React from 'react';
+import React, { useEffect } from 'react';
 import PropTypes from 'prop-types';
 import { useBeforeUnload } from '../../../../../../static/js/custom_hooks';
 
-export default function BeforeUnload({enabled, isNewTab, beforeClose, closePanel}) {
-  useBeforeUnload(
+export default function BeforeUnload({onInit, enabled, isNewTab, beforeClose, closePanel}) {
+  const init = useBeforeUnload(
     {enabled, isNewTab, beforeClose, closePanel}
   );
 
+  useEffect(()=>{
+    onInit?.(init);
+  }, [init]);
+
   return <></>;
 }
 
 BeforeUnload.propTypes = {
+  onInit: PropTypes.func,
   enabled: PropTypes.bool,
   isNewTab: PropTypes.bool,
   beforeClose: PropTypes.func,
-  closePanel: PropTypes.func,
-  getForceClose: PropTypes.func,
+  closePanel: PropTypes.func
 };
diff --git a/web/pgadmin/tools/erd/static/js/erd_tool/components/ERDTool.jsx b/web/pgadmin/tools/erd/static/js/erd_tool/components/ERDTool.jsx
index f78430260e5..2061654946a 100644
--- a/web/pgadmin/tools/erd/static/js/erd_tool/components/ERDTool.jsx
+++ b/web/pgadmin/tools/erd/static/js/erd_tool/components/ERDTool.jsx
@@ -357,7 +357,7 @@ export default class ERDTool extends React.Component {
     }
   }
 
-  confirmBeforeClose(forceClose) {
+  confirmBeforeClose() {
     let bodyObj = this;
     if(this.state.dirty) {
       this.closeOnSave = false;
@@ -366,7 +366,7 @@ export default class ERDTool extends React.Component {
           closeModal={closeModal}
           text={gettext('The diagram has changed. Do you want to save changes?')}
           onDontSave={()=>{
-            forceClose();
+            this.forceClose();
           }}
           onSave={()=>{
             bodyObj.onSaveDiagram(false, true);
@@ -375,7 +375,7 @@ export default class ERDTool extends React.Component {
       ));
       return false;
     } else {
-      forceClose();
+      this.forceClose();
     }
   }
 
@@ -886,11 +886,10 @@ export default class ERDTool extends React.Component {
     return (
       <StyledBox ref={this.containerRef} height="100%" display="flex" flexDirection="column">
         <BeforeUnload
+          onInit={({forceClose})=>{this.forceClose = forceClose;}}
           enabled={this.state.is_close_tab_warning}
           isNewTab={this.state.is_new_tab}
-          beforeClose={(forceClose)=>{
-            this.confirmBeforeClose(forceClose);
-          }}
+          beforeClose={this.confirmBeforeClose}
           closePanel={this.closePanel}
         />
         <ConnectionBar status={this.state.conn_status} bgcolor={this.props.params.bgcolor}