Just done that and there is no error, however, the image upload now seems to be working too! Strange!!
Unless, what I think might've happened is that it wasn't working so I deleted all upload info, then reapplied it, and what happened is it created a file in imagesupload folder called abc123_1.jpg, and in the _thumb folder it created and image called abc123.jpg without the increment.
Is that how the upload works? For each file it needs to write, will it look into each folder it's writing to and then name+increment each file based on the content within the folder rather than based on a global name for all files being created?
If so, I might have set up my site wrong for this. I am using single column within the DB table and adjusting the path from imagesupload/abc123.jpg to imagesupload/_thumb/abc123.jpg
