Error in getting an OAuth access token

[prgrajan2302]

I'm attempting to get an OAuth access token so I can access the my scripted API using the access and  refresh token. I created an application registry for my client .and following the instructions on the page, "OAuth API request parameters" located here. I followed the similar step and its working in lower environment but not happening in  PROD, my version is TOKYO. 
on execute getting below error response

{

    "error_description": "access_denied",

    "error": "server_error"

}

and in log getting the below error.
Exception on token flow - invalid_scope: The provided OAuth token is not valid: no thrown error.

is that I am missing anything ?

[s_proskin]

Did you ever find a solution to this issue?  I'm experiencing this in one of our instances.  All others are working, except for one!

[BartekM]

We had this issue with a Workday rest API integration, fix for us was to make sure client secret and integration user password didn't have "<> () {} [] , . ; :" characters as that was messing things up