What causes javax.faces.application.ViewExpiredException?

Question

I keep getting javax.faces.application.ViewExpiredException after opening 4 tabs of a view. Each tabs is using @ViewScoped and has it's own Managed bean. I already tried the fixes that I saw on the web like implementing Serializable for each Managed bean, increasing the session timeout and

Placing this in the web.xml

<context-param>
    <param-name>javax.faces.STATE_SAVING_METHOD</param-name>
    <param-value>server</param-value>
</context-param>

<context-param>
    <param-name>com.sun.faces.numberOfViewsInSession</param-name>
    <param-value>15</param-value>
</context-param>

<context-param>
    <param-name>com.sun.faces.serializeServerState</param-name>
    <param-value>false</param-value>
</context-param>


<context-param>
    <param-name>org.apache.myfaces.NUMBER_OF_VIEWS_IN_SESSION</param-name>
    <param-value>15</param-value>
</context-param>

<context-param>
    <param-name>org.apache.myfaces.SERIALIZE_STATE_IN_SESSION/param-name>
    <param-value>false</param-value>
</context-param>

Each page that I'm using is the same as this and uses different backing bean:

<h:form>
        <p:poll interval="1" listener="#{someBean.refresh}" update="table"
            global="false" />
            <p:dataTable id="table" value="#{someBean.list}" var="e"
                rowIndexVar="rowIndex">
                <p:column headerText="" style="width: 10%">
                    <h:outputText value="#{rowIndex}" />
                </p:column>
                <p:column headerText="Description" style="width: 90%">
                    <h:outputText value="#{e.description}" />
                </p:column>
            </p:dataTable>
        </h:form>