The GarminCustomMap plugin exports the current map canvas to a .kmz-file, which is compatible with Garmin`s Custom Maps format for handheld GPS units. That way individual maps styled in QGIS can be used as background (raster) maps on the compatible Garmin GPS units, like Alpha, Astro, Dakota, Oregon, Colorado, GPSMAP 62 series, GPSMAP 64 series, GPSMAP 78 series, Edge 800, Montana, Rino, eTrex® 20 and 30.
otherwise the condition will never be met and max_y_ext may be too large leading to lines 546 to 548 returning a NULL value which will through an exception later on.
Line 527 should read
if r == int(n_rows) and n_rows_rest > 0:
not
if r == (n_rows) and n_rows_rest > 0:
otherwise the condition will never be met and max_y_ext may be too large leading to lines 546 to 548 returning a NULL value which will through an exception later on.