Fix: Convert Zip To Sb3

Do not just rename the broken file. Instead, rebuild the SB3 correctly.

Batch Mode — Convert & repair multiple ZIPs to SB3 at once, with a report of what was fixed per file.

Would you like a technical pseudocode example of how the repair logic would work, or a UI mockup description for this feature?

An .sb3 file is essentially a renamed .zip archive containing a project.json file and various assets (images and sounds). While converting between the two is common for editing, errors often occur when re-compressing the files into the Scratch format. The "Direct Conversion" Fix convert zip to sb3 fix

If you have unzipped an .sb3 file to edit its contents and need to turn it back into a functional Scratch project, follow these steps to avoid common corruption errors:

Do Not Zip the Folder: A common mistake is zipping the parent folder itself. Scratch will not recognize the file if the project.json is buried inside a sub-folder.

Select Internal Files: Open your unzipped folder, select all the individual files and folders inside (like project.json and the assets), right-click, and choose "Send to → Compressed (zipped) folder". Do not just rename the broken file

Rename Extension: Change the resulting .zip extension to .sb3.

Note: Ensure "File name extensions" are visible in your file explorer settings, or you might accidentally name it project.sb3.zip. Fixing Corrupted .sb3 Files

If your project fails to load after conversion or shows a "validation error" in Scratch, it is likely due to a bug in the JSON structure. Would you like a technical pseudocode example of

TurboWarp sb3fix: This specialized tool sb3fix checks for known failure cases (such as missing assetId properties) and automatically repairs the JSON code to make the project readable again.

Manual JSON Upload: If only the logic is broken but assets are safe, you can try uploading the project.json file directly into a new Scratch project. If the assets were already on the Scratch server, they may link up automatically. Troubleshooting Common Errors

Missing assetId: If you get an error stating a costume is missing a required property, check the project.json inside your zip. Each costume must have a valid assetId and md5ext pointing to a file in the same archive.

Case Sensitivity: Scratch is sensitive to file names. Ensure the assets in your zip match the filenames referenced in the project.json exactly. sb3fix - fix corrupted Scratch projects - TurboWarp

If you downloaded a project and it ended up as a .zip file, or if Scratch refuses to open your .sb3 file, follow these steps.