Fix the common error: "we failed card reader authentication"

The error We failed card reader authentication means that the shared secret key being used by the ISV android application to communicate with the Handpoint android SDK is incorrect.

This error can ONLY happen for ISVs that have built their own application running on the payment terminal and embedding the Handpoint Android SDK.

The shared secret key is unique per merchant (NOT per terminal) and ensures that funds are directed to the correct merchant account behind the scenes. If this error happens it means that the ISV is trying to send funds to the incorrect merchant account.

How to fix this issue?

Ask the ISV for the serial number(s) of the terminal(s) returning "we failed card reader authentication" as well as the name of the merchant
Go into the Handpoint terminal management (TMS) and search for the serial number
Open the corresponding merchant in the TMS and verify that the merchant has the same name as the one provided by the ISV. If the merchant names do not match it means that the terminals might need to be moved to another merchant.
If the merchant name is correct, copy/paste the shared secret key in an email to the merchant/ISV. In the email ask the ISV to make sure that they are using this specific shared secret.
In the same email give them the procedure to clear the cache of their application : https://handpoint.atlassian.net/wiki/spaces/PD/pages/3522658305 . If the ISV has been moving terminals between merchants, it is likely that their app and the Handpoint android SDK running on the terminal are still using a previous configuration in which case clearing the cache of the app will remove any configuration saved locally.
If the problem persists, ask the ISV/merchant to install the Handpoint Payments app, open it and process a transaction. If processing a transaction works fine it means that the issue is located on the ISV application side side.
At the same time get the terminal detailed logs from the PAX Store and forward them to Handpoint for further analysis. Note that if the ISV is using an Handpoint Android SDK version <7.0.0 the logs will only contain very few information and will most likely be irrelevant