Can\'t upload PDF file to my gigs Gallery


i dont know what is going on, i try to upload pdf file many times to my gigs but it doesnt work. fiverr said something went wrong but i have no idea what’s going on. there is so few forum about this topic. they just said i shouldnt put any symbol and stuffs, try to change the file name and reupload. i followed it and tried many times but it still not works. help me please.!!