More http requests at once at once

In my app, iam trying to post separate requests, inside for loop. It works, the server receives data, but it also responds with error 500(internal server error). Is there any way to “group” single requests, so i dont have to spam server with tons of requests?

That depends on your server. Can you send multiple “operations” at the same time? What exactly is your server doing?

The server is saving data in db. Looks like it has problem with this multiple operations, it saves data correctly, but also respond error.

I would try to put some more intelligence into the server, so that it can receive all information needed for an atomic operation in one request. I believe REST guidelines actually mandate that.