Sim800L - Avoiding 604 Error or the cause ?


I am using sim800l module successfully without a problem to send location data every 15 seconds. My problem is every few hours, for 2-3 minutes my logs show an 604 http response which means STACK BUSY, on the internet I have made many search before opening this topic but no clear cause or solution is provided. Does anyone has an idea what causes this error or how to avoid it?