I am new to mendix development I am trying to consume a rest(Put) API . I am getting this error once I have selected Custom request template and pasting my request payload.

Braces should be followed by a number of digit or another brace. As of now I have hard-coded the request with all the parameters its a valid JSON request (works fine in postman). Thanks in Advance.  
1 answers

Since Mendix uses the brace for parameterization, if you are using an opening brace - { - not for parameterization, you need to escape it with another open brace.  So if you wanted to enter {key:value} it would instead be {{key:value}. I updated your request here.