Cornerstone issue "The preview could not load due to the iframe response being incomplete. This is most often related to a plugin conflict, or customizations introducing a PHP error."

Support
#1

I’m Thomas from the Weglot Translate plugin. One of our customers is experiencing the following issue:

Error message on the Home page only “The preview could not load due to the iframe response being incomplete. This is most often related to a plugin conflict, or customizations introducing a PHP error.”
–> If he makes another page the Home page, he can edit the previously home page, but can’t edit the newly made home page
–> He tried to deactivate cache
–> The issue is only happening when Weglot Translate plugin is activated

BUT, we tried to reproduce the error on our side, (even buying a licence from you guys), and everything was working. We could not see any error.
==> Did you already see this kind of errors?
==> Can you help us to let us know where and what to look for a fix

(I can provide our mutual customer login details so you can see if you can reproduce the error and/or where to find a fix).

Thanks a lot

#2

Hi Thomas,

Please check for the following first:

  1. Ensure everything is up to date according to our version compatibility list at https://theme.co/apex/forum/t/troubleshooting-version-compatibility/195. Please follow the best practices when updating your theme and plugins. See https://theme.co/apex/forum/t/setup-updating-your-themes-and-plugins/62 for more details.

  2. If you’re using a caching plugin, clear all caches including browser cache then deactivate your caching plugin and other optimization plugins.

  3. If you’re using a CDN, please clear the CDN’s cache and disable optimization services.

  4. Test for a plugin conflict. You can do this by deactivating all third party plugins, and seeing if the problem remains. If it’s fixed, you’ll know a plugin caused the problem, and you can narrow down which one by reactivating them one at a time.

  5. Remove custom CSS, Javascript and templates.

  6. Reset your htaccess file by renaming it to .htaccess-bak. Then in WP Admin Menu, go to Settings > Permalinks and just click the Save Changes button.

  7. Contact your host to increase your allocated memory or do it yourself by adding this code in your wp-config.php

define( 'WP_MEMORY_LIMIT', '256M' );
define( 'WP_MAX_MEMORY_LIMIT', '512M' );

If none of these helps, please provide us the wordpress admin login in SECURE NOTE(key icon)

Thanks.

2 Likes
#3

Thanks Paul.

Since the customer already identified the problem happens only for him (we can not reproduce the issue, everything working fine for us):

  • when Weglot translate is activated
  • on the Home page

Could you tell me if you already experienced such issue please?

#4

Hi Thomas ,

I just tried installing Weglot Translate on my test sites and could not replicate the issue as well. The Home page works just fine.

I also checked our issue tracker and didn’t find anything with regards to Weglot translate.

Can you provide us login in Secure Note so we can take a closer look.

Thanks

#6

Ok I did not understand how the secure note worked. Could you make sure my previous message is deleted. In the secure note are the login details

#7

Hi There @Gmulti

Upon checking server configurations, I see that the PHP memory limit is still set to 256MiB. If you have already tried to increase memory limit by following the above guide, that means the hosting provider is not allowing to change memory limit manually. In that case, you will need to contact the we hosting provider directly to increase memory limit. You can check the current server configurations by head over to Dashboard -> WP Serverinfo area.

Also enable WP_DEBUG mode when, if you require further assistance (https://codex.wordpress.org/WP_DEBUG).

Let us know how it goes.

#8

Thanks guys, here are the update from the customer (TLDR go to Conclusion, can you have a look at the issue with page ID and slug maybe):

  • Renamed my Chrome profile map and created a new one on my Windows computer

  • This didn’t change anything, what I expected because on another computer (a Mac) I am experiencing the same problem. On my Ipad, however, I can edit my home page in Cornerstone with Weglot activated. However, the editor is not compatible with an Ipad so that doesn’t really help. But it is interesting to see that it works with my same WP admin account on an Ipad.
    –> My assumption is that the problem only exists on PC’s that I have used before to edit pages.

  • I had my service provider increase PHP memory from 256 to 512 Mb. Under PHP / Core it now shows:
    Directive: Memory_limit:
    Local value: 512 M
    Master value: 256 M
    –> I assume that is what you requested?
    I have changed the WP-config.php file and now it contains:
    define( ‘WP_MEMORY_LIMIT’, ‘256M’ );
    define( ‘WP_MAX_MEMORY_LIMIT’, ‘512M’ );
    define( ‘WP_DEBUG’, true );
    I no longer work with Woocommerce, so I deactivated WooCommerce, WooCommerce Email Customizer, WooCommerce Invoice Gateway. That cleans up a lot. However…

Unfortunately, it didn’t help. Still can’t edit homepage when Weglot plugin is activated.

NEXT STEPS I UNDERTOOK I restored a backup from 11th September 2018. That was before I made changes to pages, a.o. the home page.

After the backup was restored, everything worked fine. It had several outdated plugins, such as Weglot 2.07. I updated all plugins (including Weglot) and everything still worked fine.

  • What I noticed, was that my home page had ID 992 (when editing in Cornerstone, (<https://www.trainngain.com/x/#/content/992/layout<) . It had slug “home-2”. There was also a backup of home page, it had ID 2722: (<https://www.trainngain.com/x/#/content/2722/layout<). It had ALSO slug home-2.
  • Then I restored the current backup from today again and I had my revised pages and updated Plugins back. AND the problem. I noticed that my homepage has ID 2993 (<https://www.trainngain.com/x/#/content/2993/layout<) when editing with Cornerstone. So home is a different page. I renamed the slug to home-2 and made a copy of it. I tried to rename the slug of the copy also to home-2 but that didn’t work: it is changed to home-2-2 automatically. So I have no idea why I had two home pages with the same slug. In any case, I didn’t have the problem.

CONCLUSION

  • The old backup doesn’t have the problem
  • Updating the Plugins is not the cause of the problem (while updating them in the old version didn’t introduce the problem)
  • Somewhere in the process of copying and renaming names of pages, something has happened that causes the problem but I have no idea what.
#9

He also reported <https://www.trainngain.com/x/#/options< as a non working page

#10

Hey Thomas,

Thanks for the additional info. Cornerstone working in his iPad and the slug conflict are significant clues. I have tested Weglot also though and I could not replicate the issue. I’m not sure why he would copy when it’s not necessary. I tried renaming both Page Title and Slug too and the page is still editable in Cornerstone.

Since it works in his iPad, the problem could be in his browser. Please advise him to clear the browser’s cache and if he has browser extensions, they need to be temporarily deactivated for testing. Also test in other browsers including incognito mode in his PC.

Regarding the slug conflict, I’m not sure why his page was duplicating but it’s certainly not an issue with Cornerstone nor Weglot. If he has a page duplicator plugin, that could be the cause. The duplicate will not work because Cornerstone data is tied to the original page only.

If he’s using the duplicated page as a template, he should use the Template Manager instead.

Is the “options page x/#/options not working” also connected to Weglot conflict in his site? Please tell him to reset his htaccess file by renaming it to .htaccess-bak. Then in WP Admin Menu, go to Settings > Permalinks and just click the Save Changes button. If this does not work, please advise him to open a thread here and give his WordPress Admin and FTP credentials in a Secure Note and also post the URL of this thread for reference.

Thanks.

#11

Thanks a lot Christian, I’m passing the info to the customer and I’ll get back to you.

#12

You’re welcome, Thomas.

#13

Hi Christian, this is Paul, the user of the website.
You’ve asked to reset the .htaccess file.
I can’t find .htaccess file. I have used 2 different FTP programs, switched “show hidden files” on, and tried to generate a new one by pressing the save button on the permalinks screen. Without result.
I have restored the backup that worked, and in this version also I can’t see a .htaccess file.
Your advice to clear cookies etc. was of course followed. But it doesn’t help. And besides that, if I restore a backup of the Wordpress installation it works without problems. If the cookies in the browser would be the problem, that wouldn’t work.

#14

Hello @lex,

Thanks for updating the thread.

Please take a look at following article to locate and editing .htaccess file.

https://www.shoutmeloud.com/how-to-edit-your-wordpress-htaccess-file.html
https://www.greengeeks.com/tutorials/article/tips-on-finding-your-wordpress-htaccess-file/

You also have the option of getting in touch with the hosting provider and request them to rename .htaccess file for you.

Let us know how it goes.

Thanks.

#15

Finally I was able to rename the .htaccess to .bak and create a new one by saving in the Permalink screen. I was using two FTP programs but non of them let me see .XXX files. Unfortunately, that didn’t solve the problem.
What I was able to find out meanwhile is the following:

On Windows 10 PC
Problem exists with Chrome all Chrome accounts
Problem exists with Firefox
Problem Doesn’t exist with Edge

On Windows 10 notebook
Problem exists with Chrome
Problem doesn’t exist with Edge

On Macbook Pro
Problem exists with Chrome all account
Problem exists with Safari

So on the computers that I have, Edge doesn’t give the problem.
Does that help?

#16

Hey @lex,

If the problem is not the cache, browser extensions usually cause such an issue. Maybe you have browser extensions in Chrome, Firefox and Safari that is not installed in Edge? I’ve also mentioned to check browser extensions previously.

Please also give us WordPress Admin level access in a Secure Note. Right now, I get this permission error.

We need to check if Cornerstone’s working on our end because if that is the case, you have a setting in your browser that breaks Cornerstone.

Thanks.

#17

I have given the account that you know of admin rights. Please check again.

For your information: Just unpacked a brand new Macbook Pro and freshly installed Chrome on it. Both Chrome and Firefox give the error.

#18

Hello @lex,

Thanks for updating the thread. :slight_smile:

Can you please allocate administrator level access to the username that you have shared? As the account does not has admin level access I really can’t test Cornerstone.

Thanks.

#19

Hi! Sorry for the inconvience, I updated the admin rights. Please check again.
How can I change my profile name on this forum? I am not Lex but Paul. And I don’t get any notifications if a new message or reply is added to this topic. Thanks!
Paul

#20

Hello Paul,

Please go to your profile (https://theme.co/apex/forum/u/lex) and find the preference tab. Make your that notifications were set and enabled in your account. You can also change your profile name and other details too.

Back to your issue, I was able to logged in and edited some of the pages. I created a test page with no issues at all. I even edited some of your pages. I only encounter the issue in your homepage. I am suspecting that there is something that you have added in your homepage that triggers the issue.


Please try to recreate your homepage by creating a new page. You can re assign this new page again as your homepage once your done. And if you want to check out that elements you have added in your current homepage, you can use the skeleton mode to edit the page for faster response and easy access of the elements on the preview area.

Hope this helps.

#21

Hi RueNel,
I am sorry but can’t find the option to change the username from @lex to @Paul.
Meanwhile I found the option to get notified when new responses come in (would have been logical to find them under ‘notifications’ but it appears to be under ‘emails’ :smirk:

Back to the problem: I am not sure if you get the point. Indeed the problem is my home page. But, as I have explained before, the problem is ALWAYS my home page, no matter what content is in it.
If I make another page my home page, the problem shows up in that other page. If my current Home page is no longer my home page, I can edit it without problems.
So again, it seems that the problem lies not in the page itself, but in the fact that the page is labeled “home page”.