Unable to open any page after AEM 6.1 to 6.3 upgrade

Hi,

We Upgraded the Author environment from AEM 6.1 to AEM 6.3.

Getting the below errors recursively and also unable to open any page with "/editor.html/".

05.09.2017 17:11:08.940 *ERROR* [104.103.70.205 [1504602668940] GET /mnt/overlay/granite/ui/content/shell/header/actions/pulse.data.json HTTP/1.1] org.apache.felix.http.jetty Exception while processing request to /mnt/overlay/granite/ui/content/shell/header/actions/pulse.data.json (java.lang.NullPointerException)

java.lang.NullPointerException: null

        at org.apache.sling.engine.impl.SlingMainServlet.service(SlingMainServlet.java:201)

        at org.apache.felix.http.base.internal.handler.ServletHandler.handle(ServletHandler.java:85)

        at org.apache.felix.http.base.internal.dispatch.InvocationChain.doFilter(InvocationChain.java:79)

        at org.apache.sling.i18n.impl.I18NFilter.doFilter(I18NFilter.java:138)

        at org.apache.felix.http.base.internal.handler.FilterHandler.handle(FilterHandler.java:135)

        at org.apache.felix.http.base.internal.dispatch.InvocationChain.doFilter(InvocationChain.java:74)

        at com.adobe.granite.license.impl.LicenseCheckFilter.doFilter(LicenseCheckFilter.java:308)

        at org.apache.felix.http.base.internal.handler.FilterHandler.handle(FilterHandler.java:135)

        at org.apache.felix.http.base.internal.dispatch.InvocationChain.doFilter(InvocationChain.java:74)

        at org.apache.felix.http.sslfilter.internal.SslFilter.doFilter(SslFilter.java:96)

        at org.apache.felix.http.base.internal.handler.FilterHandler.handle(FilterHandler.java:135)

Please suggest how to fix this?