Save Conflict error while trying to Update item in RER

Question

Hi,

 

I have a scenario to update a title based on some calculation in Item Updating of Remote event receivers in Sharepoint online.I am getting an error like 

 

"Save Conflict. Your changes conflict with those made concurrently by another user. If you want your changes to be applied, click Back in your Web browser, refresh the page, and resubmit your changes.".

 

It is like same Item trying to update by multiple users.Any help is appreciable.Thanks in Advance I have attached the img screen shot for reference.