I'm uploading a file with the filename Jorchr-Malmö_rådhus.jpg and in Chrome it works, in Firefox it doesn't work.

I'm getting a PDOException in the logs:
PDOException: in drupal_write_record() (regel 6975 van /home/johnny/workspace/amber3/includes/common.inc).

After I modify this line:
if ($.browser.safari) {

in dragndrop_uploads.js

into:
if ($.browser.safari || $.browser.mozilla) {

it does work.

I wonder if we even need this line as without it, it also works and IE doesn't give an error.