This has been going on for quite a while now. At some point a new version was released, and ever since GIMP will not update (all other portable apps will though.
First off: Plenty of space available on the USB stick (Sandisk Extreme 3.0 16GB, 6GB free)
When going to update GIMP Portable the file starts downloading as expected, but then stops at 61,968kb of 61,972kb. it stops for an extended period of time, and then fails with the current error message:
Download Error: File Open error on file
Steps to reproduce: Simply try to upgrade GIMP from a previous version using the Portable Apps Platform.
This has been repeatable for a long time now, but I never reported it, as I thought it was an obvious bug, which would be fixed shortly. Now many weeks (months?) later, I figured I'd file a report.