Error loading sprite asset in 3.4 (converted from 3.6)

This project was actually in 3.6 but was converted to 3.4. The following error is logged and none of the assets are loading. What can I do to make this work?

[Asset DB] Importer exec failed: C:\CocosDashboard_1.2.2\resources\.editors\Creator\3.4.2\resources\resources\3d\engine\editor\assets\primitives.fbx
at ImportTask.importAsset (C:\CocosDashboard_1.2.2\resources\.editors\Creator\3.4.2\resources\app.asar\node_modules\@editor\asset-db\libs\task.ccc:1:2434)
at processTicksAndRejections (internal/process/task_queues.js:93:5)
at async ImportTask.exec (C:\CocosDashboard_1.2.2\resources\.editors\Creator\3.4.2\resources\app.asar\node_modules\@editor\asset-db\libs\task.ccc:1:596)
at async ParallelQueue._generate (C:\CocosDashboard_1.2.2\resources\.editors\Creator\3.4.2\resources\app.asar\node_modules\@editor\asset-db\libs\asset-db.ccc:1:2643)


You can delete the folder like this and reopen the project.