sb3fix is able to resolve some common problems that can corrupt Scratch projects and make them no longer load. sb3fix is NOT perfect and we can't guarantee it will get your project back, but it's worth a shot. Just input the sb3 file into the input below.
Please get your project to us so we can try to fix it for you. If you have a GitHub account, the easiest way is to open a GitHub issue and attach your sb3 file.
Open source on GitHub: https://github.com/TurboWarp/sb3fix
Files are processed locally on your computer and never sent to any server.
Some example error messages from TurboWarp that sb3fix addresses:
Error: Unknown extension: ...Could not load project: {"validationError":"Could not parse as a valid SB2 or SB3 project.","sb3Errors":[{"keyword":"type","dataPath":".targets[2].variables['32!k|mRA^e^r;{*i9Z[p-getParam,number1,r-'][0]","schemaPath":"#/items/0/type","params":{"type":"string"},"message":"should be string"}],"sb2Errors":[{"keyword":"required","dataPath":"","schemaPath":"#/required","params":{"missingProperty":"objName"},"message":"should have required property 'objName'"}]}Could not load project: {"validationError":"Could not parse as a valid SB2 or SB3 project.","sb3Errors":[{"keyword":"type","dataPath":".targets[1].costumes[0].name","schemaPath":"#/properties/name/type","params":{"type":"string"},"message":"should be string"}],"sb2Errors":[{"keyword":"required","dataPath":"","schemaPath":"#/required","params":{"missingProperty":"objName"},"message":"should have required property 'objName'"}]}Could not load project: {"validationError":"Could not parse as a valid SB2 or SB3 project.","sb3Errors":[{"keyword":"type","dataPath":".targets[1].sounds[0].name","schemaPath":"#/properties/name/type","params":{"type":"string"},"message":"should be string"}],"sb2Errors":[{"keyword":"required","dataPath":"","schemaPath":"#/required","params":{"missingProperty":"objName"},"message":"should have required property 'objName'"}]}Could not load project: {"validationError":"Could not parse as a valid SB2 or SB3 project.","sb3Errors":[{"keyword":"type","dataPath":".targets[2].blocks['b'].inputs['MESSAGE'][1]","schemaPath":"#/definitions/optionalString/oneOf/0/type","params":{"type":"string"},"message":"should be string"},{"keyword":"type","dataPath":".targets[2].blocks['b'].inputs['MESSAGE'][1]","schemaPath":"#/definitions/optionalString/oneOf/1/type","params":{"type":"null"},"message":"should be null"}, ...}],"sb2Errors":[{"keyword":"required","dataPath":"","schemaPath":"#/required","params":{"missingProperty":"objName"},"message":"should have required property 'objName'"}]}Could not load project: {"validationError":"Could not parse as a valid SB2 or SB3 project.","sb3Errors":[{"keyword":"enum","dataPath":".targets[0].name","schemaPath":"sb3_definitions.json#/definitions/stage/properties/name/enum","params":{"allowedValues":["Stage"]},"message":"should be equal to one of the allowed values"}],"sb2Errors":[{"keyword":"required","dataPath":"","schemaPath":"#/required","params":{"missingProperty":"objName"},"message":"should have required property 'objName'"}]}Could not load project: {"validationError":"Could not parse as a valid SB2 or SB3 project.","sb3Errors":[{"keyword":"minItems","dataPath":".targets[0].costumes","schemaPath":"#/properties/costumes/minItems","params":{"limit":1},"message":"should NOT have less than 1 items"}],"sb2Errors":[{"keyword":"required","dataPath":"","schemaPath":"#/required","params":{"missingProperty":"objName"},"message":"should have required property 'objName'"}]}Could not load project: {"validationError":"Could not parse as a valid SB2 or SB3 project.","sb3Errors":[{"keyword":"required","dataPath":".targets[0].costumes[0]","schemaPath":"#/required","params":{"missingProperty":"assetId"},"message":"should have required property 'assetId'"}],"sb2Errors":[{"keyword":"required","dataPath":"","schemaPath":"#/required","params":{"missingProperty":"objName"},"message":"should have required property 'objName'"}]}The best way to see if you're in luck is to just try it.