Help With Image Upload Customization

[mcdanieldesign]

I am a print company and I would like my clients to upload their own design in the picture upload section of the Customization Field. Sometimes, the files can get large (150,000 bytes). With my current Prestashop store, I tried to upload a file. When I clicked "Save", the page refreshed to the same page (product.php?id_product=12) except the page is blank. Can you please help me solve this issue. I have also tried to change the customer upload file size settings in the back office.

Please help!

Thanks, Josh