[ADMIN] postgresql : could not serialize access due to read/writedependencies among transactions

Hi , 

I have problem about  this issue ; 

could not serialize access due to read/write dependencies among transactions

A message app like whatsapp i decided to use isolation level serializable if i use other transaction levels many conversations started with same number (think about whatsapp web sidebar multipling with same number every message).

I also add an index to my query and my query's execution plan don't use seq scan .

How can i solve this issue ? Can i solve this on db orr on app  ?