Hi there,
We are sorry this is happening to you.
If possible, would you be able to share the screenshot of the error message?
Please ensure the files you're selecting to upload are .OTF & .TTF format only, as Adobe Express allows these formats.
Also, if the issue persists, try clearing the cache/cookies of the browser you're working on? You may even try uploading from a different browser, or its incognito/private mode?
Please keep us in the loop on how it goes!
Thanks
Amitej.