Develop Reference

refresh access token for google calendar api using javascript (react)

i am using the google calendar api to write events to my organization's calendar, but i cannot figure out how to refresh the access token so that my program can use the calendar for more than an hour at a time.
to recreate the error:
generate oauth client id and client secret from your project's google cloud console
select calendar and calender.events scope at https://developers.google.com/oauthplayground
exchange the Authorization Code generated by Google's OAuth Playground for a refresh token and a temporary access token
list https://developers.google.com/oauthplayground as a valid redirect uri for your client on your project's cloud console
attempt to refresh your access token using your client id and client secret from your cloud console
THE PROBLEM
Google's OAuth playground access token expires after 3600s (1hr). I am able to refresh the access token using google's stand-in client credentials, but when I try to make the request (either from the playground itself or from postman), I am met with the following error message
{
"error_description": "Unauthorized",
"error": "unauthorized_client"
}
I have verified that the oauth playground is listed as a valid redirect uri for my client in the cloud console. I have also compared my POST request to the one google sends when refreshing the access token with placeholder credentials to ensure that I am sending all necessary params.
REQUESTS/RESPONSES
POST request on Oauth playground using google's default client credentials
POST /token HTTP/1.1
Host: oauth2.googleapis.com
Content-length: 223
content-type: application/x-www-form-urlencoded
user-agent: google-oauth-playground
client_secret=************&grant_type=refresh_token&refresh_token=1%2F%2F04qg5N0zhIRbPCgYIARAAGAQSNwF-L9IrTEZny7y_4wpbjLUh7ImtWRu473AQeTG3NG49ogQVzDZJe99BnS1TwFjwX7S2mNbLOYQ&client_id=407408718192.apps.googleusercontent.com
Response from Google's oauth playground when making the above request
HTTP/1.1 200 OK
Content-length: 385
X-xss-protection: 0
X-content-type-options: nosniff
Transfer-encoding: chunked
Expires: Mon, 01 Jan 1990 00:00:00 GMT
Vary: Origin, X-Origin, Referer
Server: scaffolding on HTTPServer2
-content-encoding: gzip
Pragma: no-cache
Cache-control: no-cache, no-store, max-age=0, must-revalidate
Date: Wed, 31 Aug 2022 22:13:53 GMT
X-frame-options: SAMEORIGIN
Alt-svc: h3=":443"; ma=2592000,h3-29=":443"; ma=2592000,h3-Q050=":443"; ma=2592000,h3-Q046=":443"; ma=2592000,h3-Q043=":443"; ma=2592000,quic=":443"; ma=2592000; v="46,43"
Content-type: application/json; charset=utf-8
{
"access_token": "ya29.a0AVA9y1sTkPpmJIHvIBNODwdXr36hzumPEmoJGFBB1y29SZVwiE_QBy7RuTjDNzPkKyBOJ7RD1LBceTooeUZuNl-wN5dkyqsjFF5ynMkcShwG_yADXazPUFXngsSGuW_WRuVR01s9FOnv2N5gzkPldvQEtLaZaCgYKATASAQASFQE65dr8ZDuFe5BQyBG8ostdxK5ObQ0163",
"scope": "https://www.googleapis.com/auth/calendar.events https://www.googleapis.com/auth/calendar",
"expires_in": 3599,
"token_type": "Bearer"
}
POST request to google's Oauth playground using MY client credentials
POST /token HTTP/1.1
Host: oauth2.googleapis.com
Content-length: 279
content-type: application/x-www-form-urlencoded
user-agent: google-oauth-playground
client_secret=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&grant_type=refresh_token&refresh_token=1%2F%2F04qg5N0zhIRbPCgYIARAAGAQSNwF-L9IrTEZny7y_4wpbjLUh7ImtWRu473AQeTG3NG49ogQVzDZJe99BnS1TwFjwX7S2mNbLOYQ&client_id=804898855072-r91v64ojblf83if1pe9f8vr4mumubecc.apps.googleusercontent.com
Response from Google's oauth playground when making the above request
HTTP/1.1 401 Unauthorized
Content-length: 75
X-xss-protection: 0
X-content-type-options: nosniff
Transfer-encoding: chunked
Expires: Mon, 01 Jan 1990 00:00:00 GMT
Vary: Origin, X-Origin, Referer
Server: scaffolding on HTTPServer2
-content-encoding: gzip
Pragma: no-cache
Cache-control: no-cache, no-store, max-age=0, must-revalidate
Date: Wed, 31 Aug 2022 22:16:15 GMT
X-frame-options: SAMEORIGIN
Alt-svc: h3=":443"; ma=2592000,h3-29=":443"; ma=2592000,h3-Q050=":443"; ma=2592000,h3-Q046=":443"; ma=2592000,h3-Q043=":443"; ma=2592000,quic=":443"; ma=2592000; v="46,43"
Content-type: application/json; charset=utf-8
{
"error_description": "Unauthorized",
"error": "unauthorized_client"
}
Any guidance is greatly appreciated. Google seriously needs some better docs!

unauthorized_client
Normally means that the client id and client secrete you are using with a refresh token is not the client id and client secret that were used to create it.
You should not be using playground to create tokens. You should be creating them in your app and refreshing them in your app.
Remember you can not refresh an token using a client side language. I am not a reactJs dev so if this is running client side that could also be the cause of your error. Use a server sided language.

Downloading a file with html anchor tag fails for "Failed - No file"

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HTTP/1.1 200 OK
X-Powered-By: Express
content-type: application/octet-stream
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Cache-Control: no-cache
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Expires: -1
Server: Microsoft-IIS/8.0
X-AspNet-Version: 4.0.30319
X-SourceFiles: =?UTF-8?B?XFxwc2ZcSG9tZVxEb2N1bWVudHNcR2l0SHViXFNvdXJjZVxDaGVyaXNoQXF00XJpc2guQXBpXGFwaVxjaGlsZFxsaXN0?=
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Date: Fri, 13 Mar 2015 09:02:35 GMT
Content-Length: 577
[{"result":"FooBar"}]