PROBLEM:

"N/A" or "NOT AVAILABLE" appears next to a database on a Garmin G500/600.

CAUSE(S)/RESOLUTION(S):
This can occur if the database is not present on the SD card, is incompatible with the GDU software version of the G500/600, or an incorrect system ID has been applied to the service.

Make sure the SD card is inserted into the correct slot on the G500/500. The card with the Aviation/Navigation database should be inserted into the top slot. All other databases should be transferred to the supplemental database card, which is inserted into the bottom slot.

The obstacles and terrain databases are compatible with specific GDU software versions. The 9as terrain database for the G500/600 is compatible with GDU software version 3.00 to 6.99. The 4.9as terrain database for the G500/600 is compatible with version 7.00 or newer. The 6as terrain database for the G500H is compatible with version 4.00 to 6.99. The 2.5as terrain database for the G500H is compatible with version 7.00 or newer. Additionally, software version 7.00 and newer requires a different format of the obstacles database. JDM will indicate in the description of the coverage if the obstacles database is for software version 7.00 or newer (as shown in the image below).

If a System ID has been assigned to the service, make sure it matches the System ID on the unit.

Refer to the following article for guidance on how to locate the software version and System ID of a Garmin device:
How to find the software version and System ID of a Garmin device