Hi Trinay

please trigger and its helper class are as below  :   

Trigger:

trigger Account_After_Update on Account (after update) {

id CurrentuserProfile = UserInfo.getProfileId();
String UserProfileName = [select name from profile where id=:CurrentuserProfile limit 1].name;

Set<Id> accountIds = new Set<Id>(); //This set is used to fetch Account Ids
Map<Id, String> newOwnerIdsMap = new Map<Id, String>();//Map to fetch New Owner Ids aginst Acoount Id's

accountIds.clear();
for (Account a : Trigger.new) {
system.debug('a.OwnerId$$$'+a.OwnerId);
//Condition for processing the trigger
if (a.OwnerId != Trigger.oldMap.get(a.Id).OwnerId  ) ) {
newOwnerIdsMap.put(a.Id, a.OwnerId);
accountIds.add(a.Id);
system.debug('a.Id$$$'+a.id);
}
}

Account_Triggers classobject =New Account_Triggers();
classobject.AccRltdObjOwnChangeMethod(accountIds,newOwnerIdsMap);

}

Helper Class Method:

public void AccRltdObjOwnChangeMethod (Set<Id> accountIds, Map<Id, String> newOwnerIdsMap){


if (!accountIds.isEmpty()) {
//SOQL to get Contact,Contacts, Open Activities and Opportunities for all updated Accounts
for (Account act : [SELECT Id, (SELECT Id, OwnerId FROM Contacts), (SELECT Id, OwnerId FROM Contracts),(SELECT Id, OwnerId FROM Opportunities),(SELECT Id, OwnerId,Status__c FROM events where isrecurrence = true and RecurrenceActivityID 1= null),(SELECT Id, OwnerId,Status FROM tasks) FROM Account WHERE Id in :accountIds]) {

//Updating Contact Owner with the Accounts New Ownerrelated to the Account
for (Contact c : act.Contacts ) {
c.OwnerId=newOwnerIdsMap.get(act.id);
listContactObj.add(c);
}

//Updating Contract Owner with the Accounts New Owner related to the Account
for (Contract c : act.Contracts) {
c.OwnerId=newOwnerIdsMap.get(act.id);
listContractObj.add(c);

}
//Updating Opportunity Owner with the Accounts New Owner related to the Account
for (Opportunity o : act.Opportunities) { //for all opportunities
o.OwnerId =newOwnerIdsMap.get(act.id);
listOpportunityObj.add(o);
}

//Updating Open Tasks Owner with the Accounts New Owner related to the Account
for (task t : act.tasks) {
if(t.status=='Open' || t.status == 'Scheduled'){
t.OwnerId =newOwnerIdsMap.get(act.id);
listTaskObj.add(t);
}
}
//Updating Open Events Owner with the Accounts New Owner related to the Account
for (Event e : act.events) {

if(e.status__c=='Pending' || e.status__c == 'Scheduled'){
e.OwnerId =newOwnerIdsMap.get(act.id);
listEventObj.add(e);
}
}

System.debug('$$$$$Events List'+listEventObj);
}

try {
update listContactObj;
update listContractObj;
update listOpportunityObj;
update listTaskObj;
update listEventObj;
}

catch(Exception e) { //catch errors
}
}

Im Facing an error while trying to update and the error is "Apex Event trigger cannot handle batch operations on recurring events."