Welcome to the Asana Community Forum @anon58991243 
The file size is max 100mb? And it is a supported file format?
Have you tried to open Asana in a different browser to see if the same happens?
I recommend also going through the other troubleshooting steps here: Asana supported browsers and troubleshooting steps | Product guide • Asana Product Guide
If it persists, please contact the Asana support team so they can investigate further: How to contact our Support Team 