Too many positions for the file format
The format being written allows only a limited number of positions per file, and the list has more.
Why it appears
The limit is a property of the format, not of RouteConverter. Some formats cannot store more than a certain number of positions in a single file.
Split
Write several files, each within the limit. Press Split to create multiple files that together hold all positions.
Reduce
Write one file with the number of positions reduced to the limit. Reduce keeps an even sampling — every Nth position across the whole list — so the shape of the track survives. Note that it deletes the other positions from the open position list, not only from the file being written; Edit → Undo steps that back.
Ignore
Write the file as is and accept that some devices or programs may not read it. Press Ignore to proceed.
Cancel
Press Cancel to leave the file unwritten.
Thinning a list yourself
If you would rather control which positions go, see Delete duplicate positions.