Even with the right tools and methods, you may encounter problems when converting ZIP to SB3. Here are common issues and solutions:
If you manually added images or audio files while the project was unzipped, ensure they match the exact filenames and MD5 hashes specified inside the project.json file. If the JSON file doesn't point to them, Scratch will ignore them or crash upon loading.
: If you manually edited the code text, a missing comma, bracket, or quotation mark will corrupt the file. Use a free online JSON validator to ensure your syntax is correct before compressing. convert zip to sb3 updated
: This usually happens if the project.json is inside a folder within the ZIP. The project.json must be at the top level (root) of the archive.
Here’s a quick troubleshooting checklist: Even with the right tools and methods, you
In 95% of cases, converting a ZIP to an SB3 is as simple as renaming the file. No actual decompression or re-compression is required. The file contents are already correct; only the name is wrong.
Whether you use online tools or offline software, ensure you're using the latest versions for compatibility with the current Scratch 3.0 file format. The SB3 format has specific requirements for JSON structure and file packaging that may be affected by updates to Scratch itself. : If you manually edited the code text,
Once renamed, navigate to the Scratch MIT Editor, click > Load from your computer , and select your newly created .sb3 file. Method 2: Re-archiving Unzipped Scratch Assets