Too many waypoints in a route can create error in calculating your route too.
Quote Originally Posted by Garmin support example for zumo 350
Up to 200 waypoints can be used when creating a custom route on your device. However, this will depend on the length of the route. If you were to use 200 waypoints and the total distance was a few hundred miles, it is likely that this would be calculated properly. Due to memory constraints within the device, you may receive a route calculation error if you attempt to insert 200 waypoints into a route that is more then a few hundred miles. To avoid this possible issue, please break your single custom route into multiple routes.
IMHO you planned a too long route, as said, split the route into 2 or more parts and it will work.
The device cannot calculate a route from Hungary to Spain in one part.
For example, if you are entering a cross-country trip, create a route for each day of travel instead of plotting in one long, continuous route.
Additionally your device will not route across open water (unless ferries are programmed in), nor will it route across different map sets. In both cases you will get the " not enough memory" error.
Check you have a basemap installed too and that all the installed maps you want to drive in your trip are routable.

Note: .PNX file seems to have to do with voice recognition in Kenwood devices, it is needed for search by voice for addresses.