public with sharing class CaseDetails {
    
    public List<Solution> lstSolution= new List<Solution>();
    public List<CaseComment> lstComment = new List<CaseComment>();
    public List<EmailMessage> lstEmails = new List<EmailMessage>();
    public List<attachment> lstattachment = new List<attachment>();
    public boolean displayPopUp{get;set;} // set Variable for pop up show hide
    public boolean displayPopUp2{get;set;}  // set Variable for pop up show hide 
    //public List<attachment> lstattachment2 = new List<attachment>();
    //public String[] countries = new String[]{};
    public Id objId;
    User objUser = new User();
    public boolean isGoogle { get; set; }
    public boolean isShow {get;set;}
    public boolean isEdit {get;set;}
    public ID caseID;
    public Case objCaseNew{get;set;}    
    PUBLIC STRING STREMAIL{GET;SET;}
    public string priorityValue {get;set;}
    List<string> searchInfo = new List<string>();
    List<Solution> solutionList = new List<Solution>();
    Contact objContact {get;set;}
    private string priorityPriorValue ;
    public string priorityReason {get;set;}
    public boolean panalView{get;set;} 
 
    public CaseDetails(ApexPages.StandardController stdController) {
    try{
     //CaseID = ApexPages.currentPage().getParameters().get('id');
      // objCaseNew  = new Case();
        isShow =false;
        isEdit = true;
        
        
        
        objContact = new Contact();
        objUser = [select ContactId from User where id =:UserInfo.getUserId()];
        
        
        objContact = [select name,phone,email,AccountId,Account.Name from Contact where Id =: objUser.ContactId];
        
        if(objContact.Account.Name.toLowerCase().contains('google')){
           isGoogle = true;
        }
        else{
           isGoogle = false;
        }
         objId = ApexPages.currentPage().getParameters().get('id');
         this.objCaseNew = (Case)stdController.getRecord();
         if(objId!=null)
         {
           objCaseNew  =[select id,CC_Email_Ids__c,Division__c,Priority,Priority_Change_Reason__c from Case where id=:objId];
           priorityReason = objCaseNew.Priority_Change_Reason__c;
           //panalView=true;
           STREMAIL = objCaseNew.CC_Email_Ids__c ;
           
           //priorityValue = objCaseNew.priority;
           //priorityReason = objCaseNew.priority;
           priorityPriorValue = objCaseNew.priority;
           
        /*if(objCaseNew.Priority_Change_Reason__c!=null)
        {
        
        panalView=true;
        
        }else{
        
         panalView=false;
        
        }
        */
           
           
         }
         //panalView=false;
         system.debug('objCaseNew___'+objCaseNew); 
        }Catch(Exception ee){}
     }
     
     
   
    
    
    public void openpopup()
    {
    //displayPopUp = true;
        if( priorityPriorValue =='P4' && ( objCaseNew.priority == 'P3' || objCaseNew.priority == 'P2'|| objCaseNew.priority == 'P1') ){
        objCaseNew.TAC_Engineer__c = 'Unassigned';
        displayPopUp = true;
        }
        
        if(priorityPriorValue =='P3' && (objCaseNew.priority == 'P2'|| objCaseNew.priority == 'P1') ){
        objCaseNew.TAC_Engineer__c = 'Unassigned';
        displayPopUp = true;
        }
        
        if(priorityPriorValue =='P2' && objCaseNew.priority == 'P1' ){
        objCaseNew.TAC_Engineer__c = 'Unassigned';
        displayPopUp = true;
        }
        
    }
    
    public void continuepopup()
    {
        displayPopUp = false;
        displayPopUp2 = true;
    }
    
    public List<CaseComment> getComments() {
        system.debug('case details');
        lstComment = [SELECT CommentBody, CreatedDate, CreatedById FROM CaseComment WHERE ParentId =: objId ORDER BY CreatedDate desc];
        return lstComment;
    }
    
   public List<EmailMessage> getEmails() {
        system.debug('Email details');
        lstEmails = [SELECT Status, Subject,FromAddress,MessageDate,TextBody,htmlbody FROM EmailMessage WHERE ParentId =: objId ORDER BY Messagedate desc];
        return lstEmails;
    }
    public PageReference NewComment() {
        if(objCaseNew!=null)
        {
        PageReference PgRefNewComment = new PageReference('/apex/CommentsPage?CaseID='+objCaseNew.ID);
        PgRefNewComment.setRedirect(true);
        return PgRefNewComment;
        }else{
        return null;
        }
    }
                
    public List<WrapperClassSS> getAttachments() {       
       if(templist.size() == 0){
           for(attachment a: [SELECT id,name,CreatedById,Owner.name,BodyLength,CreatedDate FROM Attachment WHERE ParentId =: objId ORDER BY CreatedDate desc] ){
                WrapperClassSS templ = new WrapperClassSS();                
                if(integer.valueof(a.BodyLength) < 1024 ){
                    templ.BLength = string.valueof(a.BodyLength)+'bytes';
                }
                else if(integer.valueof(a.BodyLength) <= 1048576 ){
                    if((math.mod(integer.valueof(a.BodyLength),1024) < 512))
                        templ.BLength = string.valueof(a.BodyLength/1024)+'KB';
                    else
                        templ.BLength = string.valueof((a.BodyLength/1024)+1)+'KB';
                }
                else if(a.BodyLength > 1048576 ){
                    System.debug('===attachment length with two decimal places==='+(decimal.valueof(a.BodyLength)/1048576).setscale(2));
                    string attsize = string.valueof((decimal.valueof(a.BodyLength)/1048576).setscale(2))+'MB';
                    if(attsize.contains('.0'))
                        templ.BLength = attsize;
                    else if(attsize.contains('.00'))
                        templ.BLength = string.valueof(a.BodyLength/1048576)+'MB'; 
                    else
                        templ.BLength = string.valueof((decimal.valueof(a.BodyLength)/1048576).setscale(1))+'MB';                       
                }   
                
                templ.att = a;
                templist.add(templ);           
            }
        }
         System.debug('List of attachments'+lstAttachment);
         return templist;
    }
    list<WrapperClassSS> templist = new list<WrapperClassSS>();
    public class WrapperClassSS{        
        public string BLength{set;get;}        
        public attachment att{set;get;}        
    }
    
    public void EditMode()
    {
       system.debug('MethodCall');
       objCaseNew  =[select id,CC_Email_Ids__c,Division__c,TAC_Engineer__c,Priority,Priority_Change_Reason__c from Case where id=:objId];
       priorityPriorValue = objCaseNew.priority;
       if(objId!=null)
       {
        isShow = true;
        isEdit = false;
       }
       
    }
    
    public void SaveData()
    {     
        displayPopUp2 = false;
        displayPopUp = false;
        isShow = false;   
        isEdit = true;
        string priorityval; 
     try{
            if(objCaseNew.CC_Email_Ids__c!=null){
                List<string> lstEmail=new List<string>();
                if(objCaseNew.CC_Email_Ids__c.contains(';')){
                    lstEmail=objCaseNew.CC_Email_Ids__c.split(';');
                }else if(objCaseNew.CC_Email_Ids__c.contains(',')){
                    lstEmail=objCaseNew.CC_Email_Ids__c.split(',');
                }
                if(lstEmail.size()>0){
                    for(integer i=0;i<lstEmail.size();i++){
                        if(i==0)
                        objCaseNew.CC_Email_Id__c=lstEmail[i];
                        else if(i==1)
                        objCaseNew.CC_Email_Id2__c=lstEmail[i];
                        else if(i==2)
                        objCaseNew.CC_Email_Id3__c=lstEmail[i];
                    }
                }else{
                    objCaseNew.CC_Email_Id__c=objCaseNew.CC_Email_Ids__c;
                }
                               
            }
         priorityReason = objCaseNew.Priority_Change_Reason__c;
         system.debug('**********objCaseNew.Priority111**********'+objCaseNew.Priority);  
         update objCaseNew; 
         system.debug('**********objCaseNew.Priority222**********'+objCaseNew.Priority);
       }
       catch(Exception ex) {
            apexpages.addmessages(ex);
            return;
        }                      
    }
    
    
    
    public void cancel(){
    isShow = false; 
    objCaseNew.Priority=priorityPriorValue ;        
    }
    
    public void cancelPopUp(){ 
    displayPopUp2 = false;
    displayPopUp = false; 
    objCaseNew  =[select id,CC_Email_Ids__c,Division__c,TAC_Engineer__c,Priority,Priority_Change_Reason__c from Case where id=:objId];
        
    objCaseNew.Priority=priorityPriorValue ;     
    }
    
    
   
}


 
It is working fine with all records but create this error for one Id,  altough that id exist in DB.