Console errors 412 Error

412 error indicates that your server code is different from your browser code (i.e metadata hash is out of date). Did you make any changes to the server (like studio change or dropdown change) while the browser tab was open? That is the usual use case when this happens. 

Thanks for reply !

I am using two server with alb or load balancing with single url. we have two instance with own server code and single database access both server.

Are you using On-Premise installation? Sometimes, studio changes or admin changes might be present only in one server, so try restarting both of your instances to see if that fixes the problem. 

On-Premise !