Knowledge Base Category Archives

Category: Troubleshooting

“File type not permitted for security reasons” error when trying to upload a gpx file

WordPress 4.7.1 introduced a bug that can cause this error. We have included a workaround for this in Maps Marker Pro v4.3, so updating to the latest version should fix the problem.

If you are on v4.3 or later and still get this error, it is most likely a problem with the GPX file itself. WordPress checks if the contents of a file match its reported MIME type and rejects the upload if they do not. Since GPX files are technically XML files, a valid XML header needs to be present. This means when you open the file with a text editor, the first line should look similar to this:

<?xml version="1.0" encoding="UTF-8" ?>

If that is not the case, adding the line should resolve the error.

Alternatively, although not recommended for security reasons, you can disable the MIME type check by adding the following code to your wp-config.php:


If you are still experiencing issues, please open a support ticket and attach your GPX file.

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Marker icon window is overlapped by map

If you want to change the icon of a marker and the icon window is hidden behind the map when clicking the “Change” button for icons, this is usually caused by a plugin conflict (some plugins do not follow best practices and embedd their javascripts and CSS files on every admin page and not just where needed).

You can either find and disable the plugin causing this or add the following code at the end your
theme´s functions.php to fix this:

/* Maps Marker Pro - fix for icon modal being hidden by other plugins or themes using jquery ui */
function mmp_icon_modal_visibility_workaround() {
    $current_screen = get_current_screen();
    if ( ($current_screen->base == 'maps-marker-pro_page_mapsmarkerpro_marker') || ($current_screen->base == 'maps-marker-pro_page_mapsmarkerpro_map') ) {
    echo '<style>.ui-dialog { z-index: 99999 !important; }</style>';
add_action('admin_head', 'mmp_icon_modal_visibility_workaround');
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Parse error: syntax error, unexpected T_OBJECT_OPERATOR in maps-marker-pro.php

Plugin could not be activated because it triggered a fatal error.
Parse error: syntax error, unexpected T_OBJECT_OPERATOR in /wp-content/plugins/maps-marker-pro/maps-marker-pro.php on line 66

If you see the error above when trying to activate Maps Marker Pro, this usually means that the PHP version used on your server is too low.

Maps Marker Pro requires at least PHP 5.6 to run properly, anyway as PHP 5.4 is already outdated and does not receive updates (including security fixes!) anymore since September 2015, we stronlgy recommend to a currently supported PHP version (7.x).

To fix this, please either switch your PHP version through your hosting control panel if possible or contact your hosting provider support to switch the PHP version for you.


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“For development purposes only” error on Google basemaps

By default Maps Marker Pro uses OpenStreetMap for maps which can be used without any mandatory API key registration. If you are using Google Maps though, you can experience the following issue, if the Google API key setup was incomplete/incorrect:

If you see the error “For development purposes only” on your map using Google basemaps, please open your browser console (e.g. by pressing the key F12 in Firefox or Chrome) and switch to the “Console” tab e to see more details about the error:

In the example above, the error is NoApiKeys, which means the mandatory Google Maps Javascript API key is missing.

Anyway most errors are related to your Google Maps Javascript API key, which is needed in order to display Google Maps properly.

So to fix this, please proceed as follows:

  1. make sure you registered a Google Maps Javascript API key, see tutorial for details. Please also make sure that you have saved your credit card details in the Google API console, which is needed since the Google ToS changes from summer 2018.
  2. if your error is RefererNotAllowedMapError please re-check step 6 from the tutorial and make sure you set the your accepted referrer for the domain where the map is embedded is configured correctly, like **

For all other errors please have a look at the error reference at where you will also find a possible solution.

If this still does not help, please open a support ticket and we will be glad to help.

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Error “Failed to send request” when trying to migrate to v4

This error indicates that there are some issues with your AJAX configuration respectively wp-admin/admin-ajax.php endpoint.

To verify this, please open the browser console (e.g. with F12 in Firefox or chrome), switch to the “Console” tab and reload the page and click on “Check migration” again to verify if there are any additional error messages:

If you do not see an error message there, please switch to the “Network” tab and reload the page and click on “Check migration” again to verify if there are any additional error messages:

From the screen above you see that the request failed with the Status (=HTTP error code) 404 – in this example, the file /wp-admin/admin-ajax.php was not available.

It is more likely though, that you will see Status 500 (= Internal Server Error) here. The 500 Internal Server Error is the general catch all error when the server throws an exception. It is the error message when no more specific error message is suitable and is in most cases directly related to a server misconfig or issue.

So what do now?

First, please try to temporarily disable all other plugins but Maps Marker Pro to verify that this issue is not caused by a plugin conflict.

If this does not help, please have a look at the server error log like PHP or Apache error log when that request is made and which might give you a clue why this error happens on your server.

If this still does not help, please check if one of the following tutorial can help you find the reasons for this server error:

If this still does not help, we´d advise to get in contact with your hosting support so that they can analyse why the request to /wp-admin/admin-ajax.php fails when trying to run the migration tool.

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