He tried re-zipping the folder. Nothing. He tried using online converters, which either demanded a credit card or returned a file that was just a corrupted cat sprite crying a single tear. One site gave his computer a pop-up ad for “miracle hair tonic.”
Select the file and press on your keyboard to edit the name. Delete .zip from the end of the name and type .sb3 . Press Return. In the prompt that appears, click Use .sb3 . convert zip to sb3 fix
Here is a comprehensive guide on how to perform the conversion and, more importantly, how to common issues that prevent Scratch from opening your file. Understanding the Relationship Between ZIP and SB3 He tried re-zipping the folder