What to do if Sigfox backend CRA rejects my new registration of a device that was already used?
If you see this, the PAC code you're trying to input into the Sigfox backend is either incorrect OR used to be correct but has since been refreshed and is different now (this happens when you register a device into the Sigfox backend - the PAC is a one-time code that is then regenerated so when you delete the device and try to register it again, it doesn't work).
There are two steps to take:
1) Go to the Devices tab in your Sigfox backend and check deleted devices. Search for the ID you're trying to register and if it is there, check the PAC code (often it will be different from the one you received when the devices were new).
2) If you cannot access the deleted devices tab or the PAC code that's in there doesn't work as well, contact the support desk of BOTH Sigfox Corp (ideally both community forums and the support desk directly) and your local Sigfox Operator.
Please understand that as much as we want to help you in this situation, we cannot as we are a device manufacturer and our access to the Sigfox backend is limited.