Note the page, block type and any recent plugin, theme or manual HTML change. Copy important text and code into a safe local file, and keep a revision or backup available. Check the public page separately: a block can display publicly while the editor cannot validate its saved structure.

1. Work on a draft or staging copy when the page is important. Select the affected block and review the recovery options shown.
2. Use Attempt Block Recovery if available, then inspect the result carefully before saving.
3. If recovery changes or removes required markup, undo it and review the block's HTML or comparison options with a developer.
4. For a missing third-party block, confirm the legitimate plugin providing it is installed and active. Restoring that dependency may be the right solution rather than converting everything to ordinary paragraphs.
5. Save only after confirming the content and layout are intact.

Converting a block to HTML can preserve markup but loses the original block's normal editing controls. It should be a deliberate fallback, not an automatic response to every warning. Rebuilding a small section with core blocks may be more maintainable if the original extension is no longer supported.

Reload the editor after saving and check that the warning does not immediately return. Preview the public page at different widths and test interactive elements. If the problem appears after every save, investigate a plugin or process that modifies the block markup.

Do not remove all invalid blocks in bulk merely to clear warnings. Each may contain valuable content. Provide support with the block type, sanitised error details and recent changes; avoid pasting private embedded tokens or customer records into a public troubleshooting request.

• Recovering an earlier post revision
• Recovering unsaved editor text after a failed update
• Using block transforms without losing important formatting
• Using the Details block for expandable content

• WordPress: Block Error Unexpected Or Invalid Content
• WordPress: Revisions