Unsupported Media Type Error

Hello, I’m trying to create a Post request, similar to another one that works just fine.
Only difference is that I have different data for 3 different scenarios, however even testing with absolutely the same data - request body is the same, it is basically the same request but I still receive this error:
“Content type ‘application/octet-stream’ not supported”

I compared the json request body and there is no difference aside the respected Id’s that are created, but they are correct…
So I fail to understand why it does not work.

I’m using If statements to change the variables , so I have 3 If’s, although testing with strictly one of them , it ends up having the same json raw data as the working collection and yet the error…also its 415 Unsupported Media Type

edit: Could it be because I’m not using dashes for some of the variables in the json raw? e.g.
“id”:{{roleId}} as I need the variable to not have " " in the request body…

Edit…So I had my headers wrong - Accept : Application/json instead of Content-Type : Application/json, all good