Common Symptoms
“Cannot Save” or “Cannot Publish” error after clicking Save
A block shows “This block contains unexpected or invalid content”
A block with no toolbar showing (no move arrows, no options)
Some blocks appear broken, blank, or with red warning icons
The page editor locks up or refuses to show the sidebar/settings
Step-by-Step Fixes
1) Use List View to Find Error Blocks
Click the Document Overview (☰) icon at the top of the editor to open a list of all blocks on the page.
Look for any block with a warning or “invalid” label.
Click the block in the list to select it.
2) Select the Block & Check Tools
With the block selected, look for its toolbar (move arrows, options).
If the toolbar is missing, press Esc, then click the block again — this often re-activate the toolbar.
If the block still shows “invalid content”, proceed to the next step.
3) Repair or Replace the Broken Block
Based on what you find:
If the block shows “Attempt Block Recovery” or “Resolve”, try those options. WordPress.org
If the error persists:
Delete the block.
Re-insert the correct block type (Paragraph, File, Heading, etc.).
Paste or re-upload the content into the new block.
4) Clear Cache / Refresh and Try Again
Save draft or press Ctrl+S (Command + S on Mac).
Reload the page editor.
Click Save.
If still fails, continue to the next section.
5) Additional Troubleshooting
Plugin conflict: Deactivate all plugins temporarily, see if the issue clears.
Theme issue: Switch to a different theme temporarily and check if editor works.
Browser cache / JS errors: Clear browser cache. Open Developer Console to see errors.
Invalid HTML or copied content: Avoid pasting raw HTML from external sources into block editor — causes “invalid content” errors.
Why This Happens
A block’s markup doesn’t match what the editor expects (e.g., extra HTML tags)
A plugin or theme has altered block behavior and created conflict.
A block was inserted but left incomplete (e.g., File block with no file uploaded).
Browser or caching issue causing editor to mis-render.
Summary
When pages won’t publish because of a block error:
Open List View to locate error block
Select block to repair or delete & re-insert
Clear cache and refresh editor, then publish again
If still failing, check plugins/themes & invalid HTML
Once the broken block is fixed, the page should publish normally.