Preserve unsaved text before investigating an update failure or an invalid JSON response in the block editor.
Steps
- Copy important unsaved content to a private local note. Record the exact message, affected post, and time; do not close the only tab containing your changes.
- In another tab, confirm that you are still signed in and can edit that item. A stale session or a role that can submit drafts but cannot publish needs a different correction from a server error.
- Check whether a small draft on another item saves. If only one item fails, inspect its recently added block or content without discarding the original.
- For a site-wide problem, inspect Tools → Site Health if your role allows it. Review REST API or loopback failures and the hosting logs for the matching time.
- If using browser diagnostics, record the failed save request’s status and response without sharing authentication headers. A login page, denied request, or server error returned instead of JSON points to different causes.
- Correct the identified session, URL, application, or filtering problem and retry a single draft save before publishing.
Check the result
Reopen the item in a separate tab and verify the saved text and intended publication state.
Before you continue
Do not disable every security rule or plugin on the live site to clear a generic error. Test a suspected component in staging and keep the original unsaved content until persistence is confirmed.
Documentation for this guidance: wordpress.org — site health screen; wordpress.org — roles and capabilities.
