Block based widgeteditor can't update "Not a valid JSON response"

[davidlarssonback]

When editing widgets with the new blockbased widgeteditor I can not update. I get the error "Not a valid JSON response".

I can publish and update posts and pages.
I can edit and update widgets from the customizer.

I have tried chaging permalink settings. Even with permalinks set to plain I still get the same error when I use the widgeteditor.

Site is running on an ISS server.

[antonvlasenko]

Hello.
Thank you for submitting a ticket.
Would you be able to provide steps on how to reproduce this issue?
And/or maybe record a screencast (take a screenshot) and upload it somewhere?
Thank you.

[sabbirshouvo]

@davidlarssonback are you using any shortcode inside widgets? If yes then please check if any of the shortcodes echo anything instead of return. If echo or output anything then the error will happen. Shortcodes should always return content.

[joegasper]

Same issue, just Widget editor fails. Tried everything you'll find on this error. Running IIS, don't have a site that it works, single or multisite. This is a screen recording of a generic site, 2021 theme. PHP 7.4 - no errors. MySQL 5.7.25.
​https://1drv.ms/v/s!AhHWmqEUaqs0hI0S7RPk4757r8ud7w?e=enfgpn

[robaxxx]

Same error here. Am also using IIS as the other two above, but wasn't aware that it might be related to that? The issue began with the new block widgets editor in 5.8.0, now on 5.8.2

The error happens when clicking Update in Appearance > Widgets. It does not happen when updating Widgets in Appearance > Customise. It also does not happen when using the Classic Widgets plugin to disable the Block editor.

Have confirmed with everything disabled and using the 21 default theme. Everything else works well. PHP 7.4.13

[cstrathmeyer]

Same issue here, but the issue began with the automatic update to WordPress 5.9.0 on January 26, 2022. I was previously running 5.8.3. Previously, I could edit theme widgets successfully via either Appearance | Widgets or Appearance | Customize.

I am using a Theme Spiral theme called TimesNews Pro.

I have the same problem with the Widget Block Editor as the OP. I can open a widget in Appearance | Widgets and I can edit the content of the widget using the widget block editor. But when I click Update, I get the same JSON error as the previous posters. The screen recording submitted by @joegasper is exactly the error message I am seeing.

Like the other posters, I can successfully edit the widget and save the new content via Appearance | Customize.

--Carl

[karmatosed]

Apologies for such a late reply on this, but in testing today I am not seeing the issue now. This might be due to a fix having happened during the time and my hope is that is the case. With that in mind, I am going to close this for now with a state of work for me. However, if this is still an issue please report back and we can decide if details need to stay on trac here or go to the Gutenberg Github repo where issues for the core editor are reported: ​https://github.com/wordPress/gutenberg.

In closing this, I am not saying an issue did not exist, it just seems that it has been resolved in my testing. Again this might be something I am missing so we can always iterate.