: Scratch’s internal extraction engine expects standard DEFLATE compression. Advanced compression algorithms (like LZMA or RAR disguised as ZIP) will crash the loader.
: Scratch expects specific naming conventions for assets within the project.json
: Open project.json with a text editor like Notepad++ or VS Code. Search for the costume name and ensure the md5ext string matches the exact file name inside your archive. JSON Syntax Corruption convert zip to sb3 fix
Try uploading this file to the Scratch online editor. If it loads, your problem is solved. If it fails, proceed to the repair methods below. Method 2: Fixing the "Compressed Folder" Structure Error
If you want to troubleshoot a specific project, let me know: What (if any) does Scratch display? Search for the costume name and ensure the
A new file appeared: `Archive.zip
: Select all the files inside the folder (do not compress the folder itself) and choose "Compress" or "Send to Compressed (zipped) folder". If it fails, proceed to the repair methods below
Rename the resulting new ZIP archive. Change the extension from .zip back to .sb3 .
Ensure all files are loose in a single workspace folder. Do not put assets into sub-folders like "Sounds" or "Images." The project.json file must sit directly alongside your audio and image assets. Step 2: Compress the Contents (Not the Folder) Open the folder containing your project files.