Error: API call in postman

Question

I'm getting following error during api call in postman. This happens only first time during api call afterwards it work successfully.

{ 
 "name": "PHP Core Warning",   
 "message": "Module 'OAuth' already loaded",   
 "code": 32,   
 "type": "yii\\base\\ErrorException",  
 "file": "Unknown",   
 "line": 0,   
 "stack-trace": [
     "#0 [internal function]: yii\\base\\ErrorHandler-handleFatalError()", "#1 {main}"   
 ]                        
}

Answer 1

try to reopen posman and check it will work

Answer 2

Is the api expecting a content-type header which you are not sending