Using a different character encoding type in the file than UTF-8 may prevent the file from being uploaded or result in special characters not being displayed in the layer attributes.
Prepare the layer in QGIS:
1. open the layer properties window
2. go to the source tab
3. select UTF-8 encoding
4. then save the vector layer to a new file
5. the file name should have no whitespace or special characters, e.g. current_border2178.shp