Problem with eventsmanagerpro activation

Hi, I just had to realize that the eventsmanagerpro is not working on ClassicPress (latest version). It is not possible to activate the plugin.
I will ask the eventsmanagerpro support if there is a chance to fix that.
But right now it not working.
If someone has any experiences with that issue I would love to get it working.
Regards Elmar


If this is Events Manager By Marcus Sykes it says it should work with WP4.8 and up. So contacting the developer would be the first option.

Can you post any error messages from the logs?


Yes it is eventsmanager pro by Marcus Sykes and I did write to Marcus yesterday and this is what he answered:

Chances are there’s something we use that’s in newer WP versions that ClassicPress doesn’t use in our license checking, I’d be interested to see. Chances are it’s not a big issue though and can be fixed. I could take a look, but given you’re not using WordPress I would likely need to check later this week as it’ll take more time to figure out.
I might set up a local CP install, having one ready to go might help speed things up drastically, depending on the issue.

I will post his next answer here.


Sounds like he’s quite willing to have a look which is very encouraging. Please keep us informed.

If you are talking to him again you might also mention that if he’s willing to keep CP-compatability going then we’d add him to our list of recommended plugins. "Must Have" Plugins List


Sure, I will ask him. He wrote to me that he is also not happy with the direction WP take things. So I think he might be open to support CP.
I’ll keep you informed.


That shouldn’t be the case really. Under the hood, ClassicPress is 100% compatible with WP4.9.9 - 4.9.12 so I wouldn’t have thought it’d make much, if any, difference. But either way, if we can get him on board, then that’d be great.


You and/or the plugin developer can also test with WP 4.9.12, in almost all cases the same issue should be present there too.


I already did test it with WP 4.9.12 and there it is working without any problems. And that is exactly what I also don’t understand.
When I have a bit more time I will check this problem too.
Hopefully the developer have the time and will let me/us know how this could happen…


My apologies, I assumed (like with almost all of our other plugin issues we’ve seen so far) that the same issue would be present on WP 4.9.x.

Since this is a premium plugin it’s not very easy for us to test. What happens when you active this plugin? (Specific error message, screenshot, etc)


I had a look at the code of the pro plugin and it is not encrypted it is open. But I’m not so good in debugging because I am more a frontend dev.
It feels like something happens while communicating with the api of but I have no errors. I avtivated logging by eventsmanger but it is quite empty. No errorlogs on the server and no errors shown when setting WP_DEBUG is true in config.php. No messages in the console…

The activation process and waht happens:

  1. After switching to CP I have the message in backend emp_options ’ Your license key does not match this plugin or website, please reactivate your site for this plugin via the settings page, or obtain a new license key manually.’
  2. I click activate and this redirects me to login form.
  3. When I write my access data and try to login I have a message “Something went wrong” and no login happens.
  4. Than I use another tab to login just using the login url ( and no problems there.
  5. Still logged in I return to the backend tab again and try to “recheck license”. Redirected to the loginform there is now the message “Event Manager Pro has already been activated on example[.de] - Redirecting” …
  6. After redirecting to cp backend the message " Your license key does not match this plugin or website, please reactivate your site for this plugin via the settings page…" stil appears and the plugin is not activated.

I hope that this help you guys a bit forward.
If I could do anything else, like settin up a dev installation, let me know.


I have to ask this…but when switching to CP, you didn’t change your domain at the same time did you? Sorry for asking such a basic question but all those messages suggest it’s a licensing problem.

You say it works on WP 4.9.12 - is that the same domain as the CP installation?

The other thing worth trying is to login to your EMP account and try deactivating the license.

Failing that, it might be useful if you could set up a temporary site with just CP and Events Manager Pro installed.

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No problem for me that you ask 'cause you don’t know how I am working :wink:
Like I wrote, I worked with WP 4.9.12 and there the licensmanager of EM Pro shows me a green message with the info that EM Pro Licens is avtive. Then I switched to CP by using the Switch to CP Plugin. I did not change the domain or anything else but in the licensmanager of EM Pro the message changed to “Your license key does not match this plugin or website…”. To check this again, I just did overwrite the CP core files (without wp-content) with WP 4.9.12 again and the message is green again…

As mentioned above, yes it is the same domain.

I did login to my eventsmanagerpro account deactivated and activated the plugin for this domain but no change. In my account it says the license is active on this site. And as I wrote in the post before, when I than click the button recheck license, I am redirected to the loginform of my em account, but I am still logged in and the system checks this and I get the message “The licens is already activated on this URL” and I am redirected to CP backend, where the message still is “Your license key does not match…”.
I even did setup a new license key for this domain, entered manually but no change.
Be sure that I did all possible actions and ways to get it activated.

I will setup an installation only with CP and Eventsmanager Pro. Let me know where to send the login data. I would also set access to the server by SFTP for you.

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Hmmm. Sounds kinda weird. I think @james is likely to understand what’s going on better than me but I’m happy to take a look.

I’ll pm you my email address for you to send me the login details.

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I’ve had a look at the website and had the same problems. But no solution…sorry.

The only error I could see was in Chrome (and Opera fwiw):

Failed to set referrer policy: The value '' is not one of 'no-referrer', 'no-referrer-when-downgrade', 'origin', 'origin-when-cross-origin', 'same-origin', 'strict-origin', 'strict-origin-when-cross-origin', or 'unsafe-url'. The referrer policy has been left unchanged.

I added

Header set Referrer-Policy "origin"

to .htaccess but this made no difference.

I did not get this error in Firefox.

I wonder if the problem could somehow be related to how the license key is hashed and stored in the database? Probably unlikely. James might be able to thrown some light on this.

@baterista would you be able to contact the developer to ask if there’s anything unusual in how it’s stored? Also, I can’t remember if you’ve already tried this but you could delete that particular key and request another one? Maybe the problem is at their end because everything certainly looks tickety-boo at the CP end.

OK, finally got to the bottom of this one. I consulted the oracle (@james) and he provided the solution.

This is a problem that has cropped up before with premium plugins as you can see at and is related to the User-Agent header. In this case, it appears that EMP is expecting requests to come from WordPress and throws a tantrum if it doesn’t.

The solution (as provided by James) is to add the following code either to a MU plugin or to functions.php:

function restore_wp_user_agent() {
    return 'WordPress/' . get_bloginfo( 'version' ) . '; ' . get_bloginfo( 'url' );
add_filter( 'http_headers_useragent', 'restore_wp_user_agent' );

After adding this, the license activated straight away.

James may want to clarify further.


It would make sense if the events people updated their key server code to look for wordpress or classicpress rather than people having to hack the useragent. Have you approached them at all?


Agreed. We only discovered what the issue is within the last hour so haven’t had chance to contact the dev yet but it’s certainly on the cards.


A big big thank you guys for resolving this issue. As I am still in contact (PM) with the head of dev Marcus I could send him this request if you want me to .
Let me know.

Thank you again :pray:


Yes, that would be great @baterista. Thanks very much.


The issue appears to be that Events Manager Pro is trying to pull the site URL out of the User-Agent header sent by the site. Since ClassicPress doesn’t send the site URL here (this is on purpose, to remove unnecessary tracking), this won’t work for ClassicPress sites.

Ideally Events Manager Pro should be sending the site URL in a separate field instead, and their server should read it from there. Otherwise people will have to use a small compatibility plugin that contains something like the above code (or potentially a more specific version that only takes effect when a request is going out to this particular server).

@baterista it may be easiest to just send their developer a link to this thread.