I'm having issues refreshing my tokens. What should I do?

Ensure that your integration follows the rules below:

• Store your tokens securely in your database, always in the same row. You can associate these with an internal user_id you create or with our credentials_id (which you can retrieve from this endpoint).
• Associate one user’s connection to a bank with a matching pair of tokens (access_token and refresh_token)
  
• Save your pair of tokens in one place only
• Make sure that other parts of your application read your tokens from the same place
• Replace the old access_token with the new one after every refresh 
• Renew tokens periodically or prior to a big batch of data requests

You can see a visualisation below:

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For the best practices of managing your tokens check this blog post here.