the Activity Stream section is making the page unpresentable to all the viewers

Activity Stream for pages tagged with India
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org.xwiki.rendering.RenderingException: Error while retrieving the notification
at org.xwiki.notifications.notifiers.internal.DefaultAsyncNotificationRenderer.render(DefaultAsyncNotificationRenderer.java:110)
at org.xwiki.rendering.async.internal.AsyncRendererJob.runInternal(AsyncRendererJob.java:93)
at org.xwiki.job.AbstractJob.runInContext(AbstractJob.java:240)
at org.xwiki.job.AbstractJob.run(AbstractJob.java:217)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
Caused by: org.xwiki.notifications.NotificationException: Fail to get the list of notifications.
at org.xwiki.notifications.sources.internal.DefaultParametrizedNotificationManager.getEvents(DefaultParametrizedNotificationManager.java:148)
at org.xwiki.notifications.sources.internal.DefaultParametrizedNotificationManager.getEvents(DefaultParametrizedNotificationManager.java:107)
at org.xwiki.notifications.notifiers.internal.DefaultAsyncNotificationRenderer.render(DefaultAsyncNotificationRenderer.java:106)
... 6 more
Caused by: java.lang.NullPointerException: A value node should have its content defined.
at org.xwiki.notifications.filters.expression.generics.AbstractValueNode.<init>(AbstractValueNode.java:57)
at org.xwiki.notifications.filters.expression.StringValueNode.<init>(StringValueNode.java:39)
at org.xwiki.notifications.filters.expression.generics.ExpressionBuilder.value(ExpressionBuilder.java:67)
at org.xwiki.notifications.sources.internal.TagNotificationFilter.filterExpression(TagNotificationFilter.java:117)
at org.xwiki.notifications.sources.internal.QueryGenerator.handleExclusiveGlobalFilters(QueryGenerator.java:273)
at org.xwiki.notifications.sources.internal.QueryGenerator.generateQueryExpression(QueryGenerator.java:168)
at org.xwiki.notifications.sources.internal.QueryGenerator.generateQuery(QueryGenerator.java:111)
at org.xwiki.notifications.sources.internal.DefaultParametrizedNotificationManager.getEvents(DefaultParametrizedNotificationManager.java:122)
... 8 more