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Invalid response

Posted: September 17, 2021 at 6:43 am

September 17, 2021 at 6:43 am


We have an issue with the registration process with Event Espresso. Once we fill the registration form, a message appears saying the following:

An invalid response as returned from the server while attempting to process your request. Please refresh the page and try again or contact support.

But, in 2 seconds, message disappears and continue to next step (checkout). And this happens again until the last step. All the process goes fine and the user is registered to the event, but it’s very annoying to see those messages.

In the log file, nothing happens. The javascript call is failing for some reason, but we can’t find why.
It happens with all the events.

Can you help us, please?



  • Support Staff

September 17, 2021 at 7:04 am

Hi there,

Can you link me to an event I can use to test this, please?

September 20, 2021 at 12:40 am

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  • Support Staff

September 21, 2021 at 5:46 am

Ok, so when you register onto an event EE use an ajax request to send the data back and get a response.

On your site, nothing is being returned on that request (it should always return at least a 0) but the request is valid. If I view the admin-ajax.php file directly it correctly returns just 0 so it looks like something else is hooking into the ajax request and returning early on those EE requests.

Any custom development for Event Espresso?

Or any custom code hooking into ajax requests on the site?

September 22, 2021 at 12:49 am

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  • Support Staff

September 22, 2021 at 2:45 am

Sorry, but nothing in the code of the plugin have been changed. All the changes we have made was in the front-end view (CSS, basically).

I didn’t ask if anything within the plugin had been changed?

CSS changes are fine and won’t cause this but the ajax requests can be hooked into by any plugin (or even the theme) so I asked if you’d had any custom development done for Event Espresso so we could start by ruling that out.

There are some other plugins running in the same WordPress. I list them here. If you know about some incompatibility with any of them, let me know, please:

I’m not aware of any issues with those plugins, however, it is still possible for them to conflict.

We have tested the project in two servers, and we’ve got the problem in both cases.

Ok, great, both using the same plugins, theme etc?

What I would do next is use the WP Health Check & Troubleshooting plugin to test this with just Event Espresso activate on a default theme.

Install the above plugin and go to Dashboard -> Tools -> Site Health -> Troubleshooting -> Enable Troubleshooting mode.

That disables all plugins and switches you back to a default theme, but only for you (the logged-in admin). In the admin bar go to Troubleshooting Mode -> Manage Active Plugins.

Enable Event Espresso and retest, same issue?

September 22, 2021 at 7:08 am

No, in Troubleshooting mode, everything works fine.

I have noticed that the problem appears when Elementor is activated.
Do you know problems like this with this plugin?



  • Support Staff

September 22, 2021 at 2:17 pm

I’m not aware of a conflict with elementor.

Can you send me the copy of elementor you are using so I can take a look?

If so either host the .zip somewhere (one the site itself for example) and include a link here for me to download, or send it to

September 27, 2021 at 4:52 am

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  • Support Staff

September 27, 2021 at 6:26 am

The code of the plugin Elementor hasn’t been changed.

I don’t use Elementor, so I don’t have a copy of Pro to review the code and see if anything stands out. If you can send me a copy I’ll take a look.

We have changed the buttons’ behavior in the events espresso plugin, to achieve the effect from white to black

I’m not sure I understand what you’ve changed.

Was the above using CSS or you’ve modified the code within the plugin?

If its just using CSS then that shouldn’t cause this issue.

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