Hi,

Tried with below code but i'm getting error as "Compile Error: Invalid field Task for SObject Account at line 29 column 27"

Can any help me out how resolve the error.

Please find below trigger.

trigger reassignRelatedContactsnActivitesnOpportunities on Account (after update , after insert) {
 
      Set<Id> accountIds = new Set<Id>(); //set for holding the Ids of all Accounts that have been assigned to new Owners
      Map<Id, String> oldOwnerIds = new Map<Id, String>(); //map for holding the old account ownerId
      Map<Id, String> newOwnerIds = new Map<Id, String>(); //map for holding the new account ownerId
      Contact[] contactUpdates = new Contact[0]; //Contact sObject to hold OwnerId updates
      Opportunity[] opportunityUpdates = new Opportunity[0]; //Opportunity sObject to hold OwnerId updates
   Task[] taskUpdates = new Task[0]; //Task sObject to hold updates
   Event[] eventUpdates = new Event[0]; //Event sObject to hold updates
     
      for (Account a : Trigger.new) { //for all records
         if (a.OwnerId != Trigger.oldMap.get(a.Id).OwnerId) {
            oldOwnerIds.put(a.Id, Trigger.oldMap.get(a.Id).OwnerId); //put the old OwnerId value in a map
            newOwnerIds.put(a.Id, a.OwnerId); //put the new OwnerId value in a map
            accountIds.add(a.Id); //add the Account Id to the set
         }
      }
     
      if (!accountIds.isEmpty()) { //if the accountIds Set is not empty
         for (Account act : [SELECT Id, (SELECT Id, OwnerId FROM Contacts), (SELECT Id, OwnerId FROM Task),(SELECT Id, OwnerId FROM Event),(SELECT Id, OwnerId FROM Opportunities WHERE IsClosed = False) FROM Account WHERE Id in :accountIds]) { //SOQL to get Contacts and Opportunities for updated Accounts
            String newOwnerId = newOwnerIds.get(act.Id); //get the new OwnerId value for the account
            String oldOwnerId = oldOwnerIds.get(act.Id); //get the old OwnerId value for the account
            for (Contact c : act.Contacts) { //for all contacts
               if (c.OwnerId == oldOwnerId) { //if the contact is assigned to the old account Owner
                  Contact updatedContact = new Contact(Id = c.Id, OwnerId = newOwnerId); //create a new Contact sObject
                  contactUpdates.add(updatedContact); //add the contact to our List of updates
               }
            }
   for (Task t : act.Task) { //for all tasks
    if(t.OwnerId == oldOwnerId){ //if the task is assigned to the old account owner
     Task updatedTask = new Task(Id = t.Id, OwnerId = newOwnerId); //create a new Task sObject
     taskUpdates.add(updatedTask); //add the task to our List of updates
    }
   }
   for (Event e : act.Evnet){//for all Events
    if(e.OwnerId ==oldOwnerId){ //if the event is assigned to the old account Owner
     Event updatedEvent = new Event(Id= e.Id, OwnerId = newOwnerId); //create a new Event sObject
     eventUpdates.add(updatedEvent); //add the event to our List of Updates
    }
   }
            for (Opportunity o : act.Opportunity) { //for all opportunities
               if (o.OwnerId == oldOwnerId) { //if the opportunity is assigned to the old account Owner
                  Opportunity updatedOpportunity = new Opportunity(Id = o.Id, OwnerId = newOwnerId); //create a new Opportunity sObject
                  opportunityUpdates.add(updatedOpportunity); //add the opportunity to our List of updates
               }
            }
         }
         update contactUpdates; //update the Contacts
   update taskUpdates; //update the Tasks
   update eventUpdates; //update the Events
         update opportunityUpdates; //update the Opportunities
      }
   
}