So i am trying to insert some account record. Token is right because get command works well. Error while Post - POST requires content-length. I am even trying to add body with JSONGenerator.
Http h1 = new Http();
HttpRequest req1 = new HttpRequest();
req1.setHeader('Authorization','Bearer '+accesstoken);
req1.setHeader('Content-Type','application/json');
req1.setHeader('accept','application/json');
JSONGenerator gen = JSON.createGenerator(true);
gen.writeStartObject();
gen.writeObjectField('name', 'Test Account');
gen.writeEndObject();
String body = gen.getAsString();
request.setBody(body);
req1.setMethod('POST');
req1.setEndpoint('url/services/data/v52.0/sobjects/account');
HttpResponse res1 = h1.send(req1);
system.debug('RESPONSE_BODY'+res1.getbody());