diff --git a/browser/src/core/Socket.js b/browser/src/core/Socket.js
index 006ba58479b2..a4453c7cc87b 100644
--- a/browser/src/core/Socket.js
+++ b/browser/src/core/Socket.js
@@ -1520,6 +1520,14 @@ app.definitions.Socket = L.Class.extend({
 
 	_onSocketClose: function () {
 		window.app.console.debug('_onSocketClose:');
+		if (!this._map._docLoadedOnce) {
+			var postMessageObj = {
+				success: false,
+				errorMsg: errorMessages.websocketconnectionfailed
+			};
+			this._map.fire('postMessage', {msgId: 'Action_Load_Resp', args: postMessageObj});
+			this._map.fire('error', {msg: errorMessages.websocketconnectionfailed, cmd: 'socket', kind: 'closed', id: 4});
+		}
 		if (this.ReconnectCount > 0)
 			return;
 
diff --git a/browser/src/errormessages.js b/browser/src/errormessages.js
index 63bbdfc1008e..3ef4d7cd0e7e 100644
--- a/browser/src/errormessages.js
+++ b/browser/src/errormessages.js
@@ -27,6 +27,7 @@ errorMessages.docloadtimeout = _('Failed to load the document. This document is
 errorMessages.docunloadingretry = _('Cleaning up the document from the last session.');
 errorMessages.docunloadinggiveup = _('We are in the process of cleaning up this document from the last session, please try again later.');
 errorMessages.clusterconfiguration = _('Your %productName cluster appear to be mis-configured or scaling rapidly - please contact your system administrator. Continuing with editing may result in multiple users not seeing each other, conflicts in the document storage and/or copy/paste problems. Expected serverId %0 for routeToken %1 but connected to serverId %2');
+errorMessages.websocketconnectionfailed = _('Failed to establish socket connection or socket connection closed unexpectedly. The reverse proxy is probably misconfigured, please contact the administrator. For more info on proxy conifguration please checkout https://sdk.collaboraonline.com/docs/installation/Proxy_settings.html');
 if (window.ThisIsAMobileApp) {
 	errorMessages.storage = {
 		loadfailed: _('Failed to load document.'),