Test connection checks your saved credentials with Paddle. Here is what each message means.
| Message | What to do |
|---|---|
| Paddle refused this API key | The key is not a Paddle Billing key for this environment, or lacks permissions. Create a new key with read and write access. If your dashboard is Classic, choose Paddle Classic. |
| Paddle did not recognise this API key | Copy the key again; it may be incomplete. |
| The sandbox client-side token should start with test_ | You pasted something else, often the public key. Copy the token from Client-side tokens. |
| Connected, but the public key is missing / not valid (Classic) | Paste the whole key from Developer Tools → Public Key. |
| Save your changes first, then try again | The test uses saved settings. Click Save Changes first. |