VF Component PageReference fails to use Platform Cache put() method, throwing a Cache.PlatformCacheInvalidOperationException

Dashboard.cls

public class Dashboard{

  /* Constructor */
  public void init() {
    this.accountWrapper = getAccount();
  }
  
  public PageReference pageRefreshData(){ 
    /*============= THIS ATTEMPT SUCCEEDS ==================*/
    try{
      Cache.OrgPartition customPartition = Cache.Org.getPartition('local.CustomData');
      customPartition.put('test', 'pageRefreshData()');
    }catch(Exception e){ System.debug('::CACHING ERROR:: '); }
    return null;
  }
  
  //========= WRAPPER/CONTAINER CLASSES ============//
    
  /* wrapper/container class */
  public class AccountWrapper{
    public String id { get; set; }
    public String name { get; set; }
    public Boolean isGroup { get; set; }

    public AccountWrapper(Account a){
      this.id = a.Id;
      this.name = a.Name;
      this.isGroup = (a.Name.contains('Group')) ? TRUE : FALSE;
    }
  }

}

dashboard.page

<apex:page sidebar="false" controller="FranchiseDashboard" action="{!init}">
  <c:Widget data-controller="{!dashboard}" widget-type="metric" widget-title="Title of widget" ... />
</apex:page>

metricController.cls

public class metricController extends Widget {

  //========= SETUP GETTERS/SETTERS ============//
  /* In order to get widget instance data we use a FluxCapacitor storage class
  to connect shared data between the Widget and this metric controller */
  public FluxCapacitor capacitor { get; 
    set{
      installCapacitor(value); /* Plugin flux capacitor instance into the widget instance */
    } 
  }
  public String metricVars { get; set; }
  
  /* FYI: here is example of using capacitor */
  public getSomeParameter(){
    return capacitor.dashboard.accountWrapper;
  }
}

Widget.cls

public abstract with sharing class Widget{

  //========= INSTANCE VARS ==========//
  public FluxCapacitor FC = new FluxCapacitor(); 
  /* NOTE: Custom solution for passing data to the metric components within a given widget instance */
  
  public PageReference repairErrors(){
    /*============= THIS ATTEMPT FAILS ==================*/
    try{
      Cache.OrgPartition customPartition = Cache.Org.getPartition('local.CustomData');
      customPartition.put('test', 'Widget.repairErrors()');
    }catch(Exception e){ System.debug('::CACHING ERROR:: '); }
    return null;
  }

  //========= WRAPPER/CONTAINER CLASSES ============//
    
  /* An exception class for widget data */
  public class WidgetException extends Exception{}

  /* Parameter wrapper/container class */
  public class Parameter{

    public String source { get; set; }
    public Integer year { get; set; }
    public String field { get; set; }
    public Boolean required { get; set; }

    public Parameter(String source, Integer year, String field, String required){
      this.source = source;
      this.year = year;
      this.field = field;            
      this.required = (required=='true'||required=='1') ? TRUE : FALSE;
    }
    public Parameter(String source, Integer year, String field){
      this(source,year,field, 'FALSE');
    }

  }

  /* DataError wrapper/container class */
  public class DataError{

    public String field { get; set; }
    public String index { get; set; }
    public String source { get; set; }
    public String message { get; set; }

    public DataError(Widget widget, Parameter param, String message){
      this.message = message;
      this.source = param.source;
      this.index = param.year;
      this.field = param.field;
    }

  }
  
}

widget.component

<apex:component controller="Widget" layout="none">
  <apex:attribute name="data-controller" assignTo="{!Capacitor.dashboard}" description="shared data from the widget to the metric subcomponents" type="Dashboard" required="true"/>
  <apex:attribute name="widget-type" assignTo="{!widgetType}" description="Type of widget component to be used [Component-Type]" type="String" required="true"/>
  <apex:attribute name="widget-title" assignTo="{!title}" description="Title for the widget block" type="String" required="true"/>
  
  <!-- Define Widget -->
  <c:WidgetTitle widget="{!this}"/>
  
  <!-- If there are errors, create a refresh button to attempt to get the data and cache it -->
  <apex:outputPanel id="errorMessage" layout="block" rendered="{!IF(IsWidgetLoaded,FALSE,TRUE)}">
    <apex:form>
			<apex:commandButton value="Refresh" action="{!repairErrors}" rerender="required_dummy_value" status="loadingWidgetData"/>
			<!-- NOTE: "rerender" attribute required for "status" to work properly, some sort of salesforce bug -->
		</apex:form>
  </apex:outputPanel>
  
  <!-- If there are no errors, attempt to load the metric component type that was requested when the widget was added to the page -->
  <apex:outputPanel id="metric-components" layout="block" rendered="{!IF(IsWidgetLoaded,TRUE,FALSE)}">
    <!-- Include Gauge Components -->
  	<c:Gauge widget="{!this}" flux-capacitor="{!Capacitor}" rendered="{!IF(Component=='gauge',TRUE,FALSE)}"/>
  	
  	<!-- Include Chart Components -->
  	<c:Chart widget="{!this}" flux-capacitor="{!Capacitor}" rendered="{!IF(Component=='chart',TRUE,FALSE)}" x-labels="{!labels}" data-grouping="{!groups}"/>
  	
  	// etc, etc...
  </apex:outputPanel>
</apex:component>