Bad Request and received error message "Invalid_client"

[TureeZhang]

Hi guys,

I follow the Sample Application guide to run this app but received a 400 Bad Request ,then I catched the exception.Response property and use Stream Reader to read the message , it says "invalid_client" just as the picture below .

these are my config in Sample Application and Nopcommerce(v3.9) ,any idea can help ?

I've already read this issue but still can't solve my problem ,this already cost me 2 days to find why but no any use of it... T_T

thx so much !!