Checked and fixed the error encountered in the extension by re-installing the Chilkat extension. Create the simple application using the code given in the Chilkat extension, test the created PHP after changing the access token, as per checking, an error is encountered, re-pasted the access token again as I might paste in the code incorrect token, test the PHP again, as per checking, new error encountered, it is telling 400 - bad request, as per searching, the error is the request has invalid syntax thus the server is not understanding it, tested the request in Microsoft graph but it is OK and returning a response, tested it as well on the postman it is also OK and returning a response, modified the request change it by calling the drive only, but still encountered the same error, check why this is encountered and what is the solution on this.