This is not an error message.

This represents the percentage of 'flight' data in memory. As an example: 'FULL 92' or some other number. After downloading the EDM by doing a DUMP NEW or ALL, you will see at the next startup the number value to the left of 'FULL' will have changed to a lower value. This is the percentage of memory filled since the last download.

On older EDM software, after downloading you will see: SAVE? N. By tapping the LF button to change the 'N' to 'Y',  and then tapping 'Step', you will reset to zero the percentage of memory filled since the last save. No data will be erased.