My vf code is :

<apex:page sidebar="false" controller="t1">
	<apex:form >
	<apex:pageBlock >
		Select Object Name &ensp;&nbsp;
		<apex:SelectList value="{!ObjList}" size="1">
          <apex:selectOptions value="{!objectList}">    
           </apex:selectOptions>
          <!-- <apex:actionSupport event="onchange" action="{!ChangeNumberOfRecordsPerPage}" reRender="table,button"/>-->
        </apex:SelectList>
        <apex:panelBar >
        	<apex:panelBarItem label="Field Values"/>
        	<apex:SelectList value="{!fldList}" multiselect="true">
        		<apex:selectOptions value="{!fieldList}">
        	</apex:selectOptions>
        </apex:SelectList>
    </apex:panelBar>
	</apex:pageBlock>
	</apex:form>
  <!--  <c:Dynamic_pagination objectName="contact" fieldName="Name,Account.name,Title">
    </c:Dynamic_pagination>
-->
</apex:page>

Controller code is:

public class t1 {

    public String ObjList{get;set;}
    public String fldList{get;set;}
	public list < SelectOption > getobjectList() { 
        list < SelectOption > options = new list < SelectOption > ();
        for(Schema.SObjectType item : ProcessInstance.TargetObjectId.getDescribe().getReferenceTo()){
            String name = item.getDescribe().getName();
            if(!item.getDescribe().CustomSetting && item.getDescribe().isAccessible() && !name.containsignorecase('orgDeleteRequest') && !name.containsignorecase('Solution') 
                && !name.containsignorecase('StreamingChannel') ){
                options.add(new SelectOption(item.getDescribe().getName(), item.getDescribe().getLabel()));
            }
            options.sort();
        }
        return options;
    }
    public list <SelectOption> getfieldList(){
        list<SelectOption> options = new list<SelectOption>();
        Schema.DescribeSObjectResult[] descResult = Schema.describeSObjects(new String[]{ObjList});
        Map <String,Schema.SObjectField> fldMap = descResult[0].fields.getmap();
        for(String K:fldMap.KeySet()){
            options.add(new SelectOption(K,K));
        }
        options.sort();
        return options;
        //System.debug(Schema.sObjectType.Account.fields.getmap());
    }
}

Complete error that I am getting is: ​Unable to Access Page
The value of the "entityName" parameter contains a character that is not allowed or the value exceeds the maximum allowed length. Remove the character from the parameter value or reduce the value length and resubmit.
Can anyone please explain why am I getting this error and how to resolve it?