Block editor page save fails with invalid JSON error
Saving a page in the block editor fails with an invalid JSON response error when a multi-step form is on the page.
Tier II · Emerging Problems that are still building up.
3 public reports · first reported 25 April 2024 · last reported 13 August 2025
What's going wrong
Several site owners using the block editor report that saving any page with a multi-step form returns an error saying the update failed because the response was not valid JSON.
AI-assisted: written with the help of AI from the reports. The idea report has the full summary.
In the idea report
- The full summary.
- The products the 3 reports are about, and how many came each month.
- Related problems.
No business has been found with this problem yet, so the report has no contacts. All sales are final — no refunds. Pricing.