Plugin’s cache cause legacy widget break

Widgets page, on hover the blank space. There is Meta widget here but invisible when this plugin’s cache page is enabled.

Click on it and showing Meta widget.

Hello,

Thank you for providing the detailed steps and your observations with the issue of the widgets being invisible on the WordPress theme you’ve chosen.

I followed your instructions and indeed replicated the issue with the BlankSlate theme. However, I also tried installing other popular themes like Astra and OceanWP, and noticed that the widgets function correctly with these themes. I’ve attached screenshots showing the widgets properly displayed with the Astra and OceanWP themes.

Testing with Astra theme:

Testing with OceanWP theme:

This leads me to believe the problem might be specifically related to the theme you are using rather than the plugin. It would be best to reach out to the theme developer for a potential fix or consider using a different theme that doesn’t conflict with the legacy widgets.

I appreciate your thorough explanation and the steps you took, which greatly helped in diagnosing the issue. If you have any more questions, feel free to ask.

Thank you!

I’ve tried with both themes you suggested, they have the same result. Legacy widgets are invisible.

Above is Astra theme.

Above is OceanWP theme.

This happens with many themes that supported legacy widgets such as my themes Bootstrap Basic & Bootstrap Basic 4 including WordPress theme Twenty Nineteen, Twenty Twenty-One are affected.
The most simple, basic, minimal theme that has tiny little few functional I created for test with Theme Check plugin, it’s named skinny (link is go to GitHub) still showing invisible widgets in admin page.

Tested with WordPress 6.6-alpha-58067 , PHP 8.1

All other plugins are deactivated.

• This reply was modified 7 months ago by vee.

From the pictures, it appears that the widgets are rendering their output in the admin area. This behavior indicates that once a widget is placed, it will render the output normally. If you need to edit the widget again, you can click on the area in the admin panel where the widget is supposed to appear, and this should bring up the editing options.

It doesn’t rendering legacy widget normally. It still invisible.

The rectangle box (without plus sign) you see in the picture is because I move the cursor on it. If I move cursor out then it still invisible.

If I disable WP-Optimize cache then everything will back to normal so it means that the cache part of this plugin breaks admin widget page.

If you tested with very simple theme that passed Theme Check and all code are correct (especially WordPress theme Twenty xxx) and works correctly if all plugin disabled, this means those themes have no problem.

Tested with Twenty Twenty-One theme. WP-Optimize page caching disabled. Everything works fine.

Tested with Twenty Twenty-One theme. WP-Optimize page caching enabled. Legacy widget invisible.

All other plugins are disabled.

Why you mark as resolved while it is not? From the tested above with WordPress official theme still have problem with your plugin page caching enabled. Isn’t that means it come from your plugin?

• This reply was modified 7 months ago by vee.

Found the problem!

From your plugin wp-optimize/cache/file-based-page-cache.php
line 141

wpo_cache_add_footer_output(sprintf("Page not served from cache %s", $not_cached_details));

If I comment out this line, the widgets load properly. This is because legacy widget load via AJAX and response should be JSON but you send out HTML comment that breaks the JSON result.

So, is this your plugin’s problem?

Please check that it is not from widget admin page or response content type is HTML before add comment on footer output.

Thank you for your patience and for providing such detailed information about the issues you’re experiencing with the WP-Optimize plugin.

I have passed all the relevant details to our development team for further analysis. They are currently working to pinpoint the root cause.

We appreciate your efforts in helping us enhance our plugin. We will keep you updated on our progress and inform you as soon as a fix is in place.

Thank you for your understanding and cooperation.

It’s 2 months but still doesn’t fix.

I apologize for the delay and inconvenience. I have checked the status, and I can confirm that the issue is still under progress. I will escalate this matter to prioritize the fix and plan it for an upcoming future release.

Thank you for your patience and understanding. I’ll post an update here as soon as the fix is implemented.

• This reply was modified 5 months ago by wpmansour.
• This reply was modified 5 months ago by wpmansour.

@okvee – I am marking this as resolved as there is nothing further we can do here.

For all plugins updates/fixes/bugs please refer to the plugins change log

At least, please remove that unnecessary HTML comment or put them in WP error log file and everything will back to normal.