Missing styles or source resources
Load vitext.css and serve the entire matching dist directory. Check source.js/codecs.js and their chunks for actual 404 responses. Verify trusted module URLs and your CSP, and use HTTP rather than file URLs. ESM imports in these guides require the local workspace build.
A mode will not switch
An invalid or stale source draft blocks mode changes. Read the status, fix/reset the draft and retain the last applied document. Disabled modes are configuration errors; switching preset is not a way to bypass validation.
A tool or plugin is missing
Check the preset and features. Simple excludes advanced modes/media/menus/plugins; Base excludes Markdown/CSS/plugins. Explicit toolbarLayout determines selected order, while overflow temporarily moves tools into ***. Table controls are contextual.
Duplicate mounts and async work
Destroy the previous instance before reuse. Await Markdown/CSS initialization and abort/discard late work after unmounting. A stale revision protects later user edits; do not retry blindly over newer content. Lifecycle, errors.