Hi,

I have been working on a page to have a mass update of owner in Salesforce.com for Leads & Opportunities. 

Based on the input(csv file) from user the code is supposed to update the Lead & Opportunity object with appropriate Owners.

However, I m getting the following error when trying to update the owner information. 

System.DmlException: Update failed. First exception on row 0 with id 006Q000000BKaeIIAT; first error: INVALID_CROSS_REFERENCE_KEY, Owner ID: owner cannot be blank: [OwnerId]

Following is the method which is being called:

public Pagereference ReadFile()
{
nameFile=contentFile.toString();
filelines = nameFile.split('\n');
system.debug('file lines: '+filelines);
system.debug('file line size: '+filelines.size());
OpptyTaskTransfer_CTE o = new OpptyTaskTransfer_CTE();
opptytoupdate = new List<Opportunity>();
try
{

for (Integer i=1;i<filelines.size();i++)
{
List<String> inputvalues=filelines[i].split(',');
if(o.isValidId(inputvalues[0].trim()))
{
listOppty.add(inputvalues[0].trim());
listUser.add(inputvalues[1].trim());
mapOpptyOwner.put(inputvalues[1].trim(),inputvalues[0].trim());
}
else
{
ApexPages.Message errormsg = new ApexPages.Message(ApexPages.severity.ERROR,'Please check the Lead Id: '+inputvalues[0].trim());
ApexPages.addMessage(errormsg);
}

}

Set<String> setUsers = new Set<String>();
setUsers.addAll(listUser);

for(String uname: setUsers)
{
if([select Id, Name,Username from User where username=:uname and isActive=true limit 1].size()!=1)
{
ApexPages.Message errormsg = new ApexPages.Message(ApexPages.severity.ERROR,'Please check the Username: '+uname);
ApexPages.addMessage(errormsg);
}
}


allUsers = [select Id,Name,Username from User where Username IN: setUsers and isActive=true];

for (String username : setUsers)
{
for(User u : allUsers)
{
if(username ==u.Username)
{
mapUser.put(u.username,u.Id);
}
}
}

for(String uName : mapOpptyOwner.keySet())
{
mapOpptyOwnerId.put(mapOpptyOwner.get(uname),mapUser.get(uname));
}

allOppty = [select Id,OwnerId from Opportunity where Id IN: listOppty];

for(Id i : listOppty)
{
for(Opportunity op : allOppty)
{
if(i==op.Id)
{
op.OwnerId=mapOpptyOwnerId.get(i);
opptyToUpdate.add(op);
}
}
}

if(!opptytoupdate.isEmpty())
{
update opptytoupdate;
ApexPages.Message succmsg = new ApexPages.Message(ApexPages.severity.INFO,'Updated '+opptytoupdate.size()+' record(s) successfully.');
ApexPages.addMessage(succmsg);
}
}
catch (Exception e)
{
ApexPages.Message errormsg = new ApexPages.Message(ApexPages.severity.ERROR,'An error has occured. Please check the file uploaded or try again later');
ApexPages.addMessage(errormsg);
}
return null;
}

I am unable to figure out the issue here. Can some one please help?

Thanks...