PHP Fatal error: ob_end_flush():

Resolved bobsled
(@bobsled)

7 months, 3 weeks ago

I’ve struck an anoying little issue on one of my sites after updating to 6.8. When I try to open the Customizer, I get a white screen. It produces this error: PHP Fatal error: ob_end_flush(): Cannot use output buffering in output buffering display handlers.

I tried deactivating all plugins, and when I rectivated them one by one, the error only occurs when W3 Total Cache is activated.

I have another site running W3 Total Cache without any issues.

But the site with the error is using subfolders. Eg:

example.com/
example.com/shop/
example.com/help/

All three sites are using W3 Total Cache.

I can only assume that there is some kind of conflict occurring. I have tried changing the basic settings in W3 Total Cache, but without any luck.

Do you have any suggestions that I can try?

Viewing 10 replies - 1 through 10 (of 10 total)

Plugin Contributor Marko Vasiljevic
(@vmarko)

7 months, 2 weeks ago

Hello @bobsled

Thank you for reaching out, and I am happy to help!
Is that the entire error message or does in indicate any specific file and line in the code?
Is Minify enabled on that website you are having issues with? And if so, can you please check the Performance>Minify page and see if the option Disable minify for logged in users is checked?
If the option is not enabled, please enable it, save all settings, purge the cache, and let me know if the problem persists.

Thanks!

Thread Starter bobsled
(@bobsled)

7 months, 2 weeks ago

Hi @vmarko ,

Thanks for getting back to me so quickly.

Here is the full PHP error:

PHP Fatal error: ob_end_flush(): Cannot use output buffering in output buffering display handlers in /home/clients/99d25ec0f0515fd8faba31adc21b928c/web/(site info removed)/wp-includes/functions.php on line 5471

I don’t have minify set, as I use Autoptimize.

I hope this information is useful for you.

Plugin Contributor Marko Vasiljevic
(@vmarko)

7 months, 2 weeks ago

Hello @bobsled

Thank you for your feedback.
Well, this is interesting indeed.

Can you please disable the settings one by one in Performance>general settings, save the settings and purge the cache after each setting is disabled and see which one might be causing the issue?

Thanks!

Thread Starter bobsled
(@bobsled)

7 months, 2 weeks ago

Hi again @vmarko

Because the three sites are linked, I tried your suggestons with Total Cache only activated on one site. I only use page and browser cache on all three sites.

But when I unticked each setting, it made no difference. The customizer loaded a white page with either one or both settings unticked and purged.

But when I deactivated the plugin, the customizer works again.

Luckily, there is no problem on the front end, and the sites all load quickly with Total Cache enabled.

It’s really a weird situation. I can usually nut out WordPress issues, but this one has me stumped.

Plugin Contributor Marko Vasiljevic
(@vmarko)

7 months, 2 weeks ago

Hello @bobsled

Thank you for your feedback.
I’ll need to look into it more as I cannot seem to replicate the behavior

I’ll let you know as soon as I have more information

Thanks!

Thread Starter bobsled
(@bobsled)

7 months, 2 weeks ago

Okay, @vmarko

No problem. I’ll wait until you have more infomation.

Plugin Contributor Marko Vasiljevic
(@vmarko)

7 months, 2 weeks ago

Hello @bobsled

Thank you for your patience

https://core.trac.wordpress.org/browser/tags/6.8/src/wp-includes/functions.php#L5471 flushing all output buffer levels and PHP is complaining about one or more buffer levels being an “output buffering display handler”.

Can you please try switching to another theme just to make sure that it’s not theme related?
Thanks!

Thread Starter bobsled
(@bobsled)

7 months, 2 weeks ago

Hi @vmarko

I change to the Twenty Twenty One theme, and yes, the customizer works with W3 Total Cache activated.

So I guess I need to revert back to Astra support again now.

Plugin Contributor Marko Vasiljevic
(@vmarko)

7 months, 1 week ago

Hello @bobsled

Thank you for your feedback.
Please make sure to check if you have any other optimization options enabled in Astra theme that may cause conflict in this case.
Let me know if it helps!
Thanks!

Thread Starter bobsled
(@bobsled)

7 months ago

Hi @vmarko

Astra support has found the problem within its theme. A new update is coming shortly. But for the time being, my staging site is using the latest development version and everything works well.

So all should be fine now, and no problems at all with W3 Total Cache.

Thanks so much for the time you took on this issue.

Viewing 10 replies - 1 through 10 (of 10 total)

The topic ‘PHP Fatal error: ob_end_flush():’ is closed to new replies.