Unable to obtain OAuth token – always invalid_client

[Benyamin Bolhassani]

Hi FatSecret Support,

I’m trying to authenticate against the FatSecret OAuth endpoint but I consistently receive the following error:

{"error":"invalid_client"}

Here are the details of my setup:

• Endpoint: https://oauth.fatsecret.com/connect/token

• Grant type: client_credentials

• Client ID / Client Secret: Using exactly as shown in my developer panel

• Scopes tested:

  • basic (still fails)

  • premier (also fails)

  • No scope (fails as well, even though docs say it should default to available scopes)

• Request format: Using the official documentation method:

  curl -u <CLIENT_ID>:<CLIENT_SECRET> \ -d "grant_type=client_credentials&scope=basic" \ -X POST https://oauth.fatsecret.com/connect/token

• Response: Always returns {"error":"invalid_client"}

• IP setup: My server’s public IP is 156.244.46.22. I have whitelisted it in the panel using CIDR notation as 156.244.46.22/32.

• Verification: I confirmed the IP using curl ifconfig.me on the same environment where I run the request.

Questions:

1. Is 156.244.46.22/32 the correct way to whitelist a single IP?

2. Is there any additional configuration required on my account to enable basic or premier scopes?

3. Are there cases where the -u client:secret syntax does not work, and instead credentials must be passed in the POST body?

Thanks in advance for your help!

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