If you encounter this error when uploading your game to itch.io, it means that the .zip file contains files whose names are not in UTF-8 format, usually due to:
Accents or special characters (á, é, í, ó, ú, ñ)
Emojis
Unusual symbols
Extremely long names
Words with non-standard encoding (some downloaded from the internet)
🔍 How to identify problematic files
Extract your exported project (HTML) to a folder.
Open PowerShell within that folder.
Run this command:
Get-ChildItem -Path ".\" -Recurse | Where-Object { $_.Name -cmatch "[^\u0000-\u007F]" }
✅ This will display all files containing invalid characters.
✅ How to fix it
Rename those files using only:
Regular letters (a–z)
Numbers
Hyphen - or underscore _
Examples:
Horror Music.mp3 → terror_music.mp3
Orcas attack a swimmer.mp4 → orcas.mp4
If you don't use those files in your game, simply delete them.
✅ Then:
Make sure to update the names within GDevelop as well, if they are used.
Re-export the HTML project.
Create a new ZIP file.
Upload it to itch.io again.
✅ Why it happens
Itch.io requires that all filenames within the ZIP file be encoded in UTF-8.
If it finds names with accents, emojis, or symbols, it displays this error and rejects the upload.
✅ Tip
Avoid using names with accents, emojis, or special characters in files or folders within your project.
✅ Done!
If you follow these steps, the error will disappear, and you'll be able to upload your game without any problems.