Yes, you read that correctly:
Scratch uses the ZIP format specification to compress the project data into a single package that is easy to share. The only difference between a .zip file and an .sb3 file is the . zip to sb3
The ZIP file does not contain a valid Scratch 3.0 structure. Perhaps it contains a single folder, or it’s a corrupted download. Yes, you read that correctly: Scratch uses the
Use the zip command in Terminal:
: Modifying the project.json to change variables or scripts that are difficult to edit in the Scratch UI. zip to sb3
You cannot just rename any ZIP to .sb3 and expect it to work — Scratch will show an error unless project.json is present and valid.