To re-authenticate your Fortnox connection in Upsales:

1. Click Settings → Fortnox → Settings tab

2. Click Delete: 

   Save
   
   
   
   
3. Login again with the same Fortnox account that you deleted the connection. It should now show "Authenticated with oAuth" and the status tab will be green
4. For any issues, please contact our support team

The Fortnox account connected from Upsales needs to have the highest possible permissions in Fortnox.