There are various reasons for this:
- Charging has been ended another way and the CPO has sent a CDR to the HBS. The HBS session was therefore closed. The EMP receives status code “400: Session is invalid” if it sends a remote stop for a session already ended.
- Charging has been ended another way and the CPO has not sent a CDR to the HBS. In this case, the response of the CPO is forwarded to the EMP.
- The charging process has not been completed. There is either a technical problem at the CPO or the HBS. Given that an error message from the CPO is forwarded by the HBS, a technical problem at the CPO is likely. The process should be tested and validated against the charging station of another CPO.