invalid requst while getting access token

Hi sagarneupane, 
 
Thanks for your post. Please allow me to extend to you a very warm welcome to the Community Forum. We are glad that you found this forum useful to your inquiry and we are sorry that you are having challenges with the error invalid request. We genuinely appreciate your patience and cooperation regarding this matter. 
 

When the error Invalid request is occurring, this can be caused by the below.

• The redirect Uri param is encoded twice or not at all.
• The redirect Uri param does not match your API key configuration that is set up in my.myob.
• One or more parameters are missing, incorrect, or badly formatted.

Also, here is one post from another user that will help you resolve this error: Invalid request getting access token. I will also send you a private message with the information and instructions that will assist you further. To access this, please click on your forum display picture in the top right-hand corner of your screen, then choose the envelope icon that appears.
 
 
Feel free to post again anytime you require further assistance. 
 
If my response has answered your enquiry, please click "Accept as Solution" to assist other users find this information. 
 
Cheers,  
Leneth