article Unable to connect to the Qlik Sense engine error displayed on Qlik Sense Hub in Official Support Articles https://community.qlik.com/t5/Official-Support-Articles/Unable-to-connect-to-the-Qlik-Sense-engine-error-displayed-on/ta-p/1717211 <P>When accessing the HUB you are getting the following error when trying to open an application in the Qlik Sense Hub<BR /><FONT face="courier new,courier"><SPAN>Unable to connect to the Qlik Sense engine. Possible causes: too many connections, the service is offline, or networking issues.</SPAN></FONT></P> <P><BR /><IMG src="https://qlik--c.um1.content.force.com/servlet/servlet.ImageServer?id=0153z000005dOd5&amp;oid=00D20000000IGPX&amp;lastMod=1556740256000" border="0" alt="User-added image" /></P> <H3><BR />Environment:&nbsp;</H3> <P><LI-PRODUCT title="Qlik Sense Enterprise on Windows" id="qlikSenseEnterpriseWindows"></LI-PRODUCT>&nbsp;#, November 2018 and late</P> <H3>&nbsp;</H3> <H3>Cause:</H3> <P>&nbsp;</P> <P><STRONG>Two possible causes...</STRONG></P> <P>1. Insufficient number of connections configured for the <SPAN>max connections </SPAN>entry in the <SPAN class="feedcommenttext"><SPAN class="feeditemtext cxfeeditemtext"><FONT face="courier new,courier"><SPAN>%ProgramData%Qlik\Sense\Repository\PostgreSQL\&lt;version&gt;\postgresql.conf</SPAN></FONT> file&nbsp;</SPAN></SPAN>located on the server hosting the&nbsp; in the Qlik Sense Repository database (PostgreSQL)<BR /><BR />2. Due to the WebSocket traffic not being allowed between the client computer and the Qlik Sense Server.<BR />You can test the websocket connectivity following this article:&nbsp;<A href="https://community.qlik.com/t5/Support-Knowledge-Base/Qlik-Sense-Websocket-Connectivity-Tester/ta-p/1716909" target="_blank" rel="noopener">Qlik Sense Websocket Connectivity Tester</A></P> <P>&nbsp;</P> <H3>Resolution:</H3> <P>&nbsp;</P> <P><STRONG>Two possible resolutions respectively...</STRONG></P> <P><BR />1. Ensure <SPAN class="feedcommenttext"><SPAN class="feeditemtext cxfeeditemtext">the </SPAN></SPAN><SPAN>max connections </SPAN>entry in the <SPAN class="feedcommenttext"><SPAN class="feeditemtext cxfeeditemtext"><FONT face="courier new,courier"><SPAN>%ProgramData%Qlik\Sense\Repository\PostgreSQL\&lt;version&gt;\postgresql.conf</SPAN></FONT> file </SPAN></SPAN>located in the Qlik Sense Repository database is correctly configured<SPAN class="feedcommenttext"><SPAN class="feeditemtext cxfeeditemtext">. The value needs to equate to the the number of nodes in the deployment multiplied by 110 (+20) as defined in the <A href="https://help.qlik.com/en-US/sense-admin/Subsystems/DeployAdministerQSE/Content/Sense_DeployAdminister/QSEoW/Deploy_QSEoW/Installing-configuring-postgresql.htm#anchor-5" target="_blank" rel="noopener">Configuring PostgreSQL - Qlik Sense for Administrators</A>.</SPAN></SPAN></P> <P><SPAN class="feedcommenttext"><SPAN class="feeditemtext cxfeeditemtext"><span class="lia-inline-image-display-wrapper lia-image-align-center" image-alt="PostgresSQL_Max_connections.gif" style="width: 800px;"><img src="https://community.qlik.com/t5/image/serverpage/image-id/45136i387FAEA4E36D7A0C/image-size/large?v=v2&amp;px=999" role="button" title="PostgresSQL_Max_connections.gif" alt="PostgresSQL_Max_connections.gif" /></span></SPAN></SPAN></P> <P>&nbsp;</P> <P>2.&nbsp;If the WebSocket traffic is blocked, you will need to reach out to your IT department to allow it. See <A href="https://community.qlik.com/t5/Qlik-Support-Knowledge-Base/Qlik-Sense-Websocket-Connectivity-Tester/ta-p/1716909" target="_blank" rel="noopener">Qlik Sense Websocket Connectivity Tester</A> and <A href="https://community.qlik.com/t5/Support-Knowledge-Base/How-To-Check-If-The-Browser-Works-With-WebSockets/ta-p/1714780" target="_blank" rel="noopener">How To Check If The Browser Works With WebSockets</A></P> <P>&nbsp;</P> <H3>Related Content:</H3> <UL> <LI><A href="https://community.qlik.com/t5/Support-Knowledge-Base/Postgres-FATAL-remaining-connection-slots-are-reserved-for-non/ta-p/1715939" target="_self">Postgres: FATAL: remaining connection slots are reserved for non-replication superuser connections</A>&nbsp;</LI> <LI><A href="https://community.qlik.com/t5/Support-Knowledge-Base/PostgreSQL-postgresql-conf-and-pg-hba-conf-explained/ta-p/1713744" target="_blank" rel="noopener">PostgreSQL: postgresql.conf and pg_hba.conf explained</A>&nbsp;</LI> </UL> Thu, 11 Feb 2021 15:20:42 GMT Bastien_Laugiero 2021-02-11T15:20:42Z Unable to connect to the Qlik Sense engine error displayed on Qlik Sense Hub https://community.qlik.com/t5/Official-Support-Articles/Unable-to-connect-to-the-Qlik-Sense-engine-error-displayed-on/ta-p/1717211 <P>When accessing the HUB you are getting the following error when trying to open an application in the Qlik Sense Hub<BR /><FONT face="courier new,courier"><SPAN>Unable to connect to the Qlik Sense engine. Possible causes: too many connections, the service is offline, or networking issues.</SPAN></FONT></P> <P><BR /><IMG src="https://qlik--c.um1.content.force.com/servlet/servlet.ImageServer?id=0153z000005dOd5&amp;oid=00D20000000IGPX&amp;lastMod=1556740256000" border="0" alt="User-added image" /></P> <H3><BR />Environment:&nbsp;</H3> <P><LI-PRODUCT title="Qlik Sense Enterprise on Windows" id="qlikSenseEnterpriseWindows"></LI-PRODUCT>&nbsp;#, November 2018 and late</P> <H3>&nbsp;</H3> <H3>Cause:</H3> <P>&nbsp;</P> <P><STRONG>Two possible causes...</STRONG></P> <P>1. Insufficient number of connections configured for the <SPAN>max connections </SPAN>entry in the <SPAN class="feedcommenttext"><SPAN class="feeditemtext cxfeeditemtext"><FONT face="courier new,courier"><SPAN>%ProgramData%Qlik\Sense\Repository\PostgreSQL\&lt;version&gt;\postgresql.conf</SPAN></FONT> file&nbsp;</SPAN></SPAN>located on the server hosting the&nbsp; in the Qlik Sense Repository database (PostgreSQL)<BR /><BR />2. Due to the WebSocket traffic not being allowed between the client computer and the Qlik Sense Server.<BR />You can test the websocket connectivity following this article:&nbsp;<A href="https://community.qlik.com/t5/Support-Knowledge-Base/Qlik-Sense-Websocket-Connectivity-Tester/ta-p/1716909" target="_blank" rel="noopener">Qlik Sense Websocket Connectivity Tester</A></P> <P>&nbsp;</P> <H3>Resolution:</H3> <P>&nbsp;</P> <P><STRONG>Two possible resolutions respectively...</STRONG></P> <P><BR />1. Ensure <SPAN class="feedcommenttext"><SPAN class="feeditemtext cxfeeditemtext">the </SPAN></SPAN><SPAN>max connections </SPAN>entry in the <SPAN class="feedcommenttext"><SPAN class="feeditemtext cxfeeditemtext"><FONT face="courier new,courier"><SPAN>%ProgramData%Qlik\Sense\Repository\PostgreSQL\&lt;version&gt;\postgresql.conf</SPAN></FONT> file </SPAN></SPAN>located in the Qlik Sense Repository database is correctly configured<SPAN class="feedcommenttext"><SPAN class="feeditemtext cxfeeditemtext">. The value needs to equate to the the number of nodes in the deployment multiplied by 110 (+20) as defined in the <A href="https://help.qlik.com/en-US/sense-admin/Subsystems/DeployAdministerQSE/Content/Sense_DeployAdminister/QSEoW/Deploy_QSEoW/Installing-configuring-postgresql.htm#anchor-5" target="_blank" rel="noopener">Configuring PostgreSQL - Qlik Sense for Administrators</A>.</SPAN></SPAN></P> <P><SPAN class="feedcommenttext"><SPAN class="feeditemtext cxfeeditemtext"><span class="lia-inline-image-display-wrapper lia-image-align-center" image-alt="PostgresSQL_Max_connections.gif" style="width: 800px;"><img src="https://community.qlik.com/t5/image/serverpage/image-id/45136i387FAEA4E36D7A0C/image-size/large?v=v2&amp;px=999" role="button" title="PostgresSQL_Max_connections.gif" alt="PostgresSQL_Max_connections.gif" /></span></SPAN></SPAN></P> <P>&nbsp;</P> <P>2.&nbsp;If the WebSocket traffic is blocked, you will need to reach out to your IT department to allow it. See <A href="https://community.qlik.com/t5/Qlik-Support-Knowledge-Base/Qlik-Sense-Websocket-Connectivity-Tester/ta-p/1716909" target="_blank" rel="noopener">Qlik Sense Websocket Connectivity Tester</A> and <A href="https://community.qlik.com/t5/Support-Knowledge-Base/How-To-Check-If-The-Browser-Works-With-WebSockets/ta-p/1714780" target="_blank" rel="noopener">How To Check If The Browser Works With WebSockets</A></P> <P>&nbsp;</P> <H3>Related Content:</H3> <UL> <LI><A href="https://community.qlik.com/t5/Support-Knowledge-Base/Postgres-FATAL-remaining-connection-slots-are-reserved-for-non/ta-p/1715939" target="_self">Postgres: FATAL: remaining connection slots are reserved for non-replication superuser connections</A>&nbsp;</LI> <LI><A href="https://community.qlik.com/t5/Support-Knowledge-Base/PostgreSQL-postgresql-conf-and-pg-hba-conf-explained/ta-p/1713744" target="_blank" rel="noopener">PostgreSQL: postgresql.conf and pg_hba.conf explained</A>&nbsp;</LI> </UL> Thu, 11 Feb 2021 15:20:42 GMT https://community.qlik.com/t5/Official-Support-Articles/Unable-to-connect-to-the-Qlik-Sense-engine-error-displayed-on/ta-p/1717211 Bastien_Laugiero 2021-02-11T15:20:42Z Re: Unable to connect to the Qlik Sense engine error displayed on Qlik Sense Hub https://community.qlik.com/t5/Official-Support-Articles/Unable-to-connect-to-the-Qlik-Sense-engine-error-displayed-on/tac-p/1854645#M4716 <P>I went through many articles, each article was explaining about web socket communication but was not clear which port/flow is getting blocked. We are using multi node deployment i.e. central node, engine, schedule and 3 proxy nodes (3 app nodes, 3 web nodes).</P> <P>We were able to investigate that port 4747 (Engine) was blocked between app nodes and web nodes. We opened the port and it all started working fine.&nbsp;</P> Tue, 02 Nov 2021 12:31:07 GMT https://community.qlik.com/t5/Official-Support-Articles/Unable-to-connect-to-the-Qlik-Sense-engine-error-displayed-on/tac-p/1854645#M4716 Lokeshb31 2021-11-02T12:31:07Z