What to do if you see the message "e-conomic is responding with an unknown error"

The cause:

This message indicates that e-conomic are having some technical challenges.

The solution:

Please contact e-conomic to ask them about the status of a fix. Of course, you are also more than welcome to contact Pleo's support team, in which case our higher-level support engineers will check if we can see a more specific message from e-conomic.