Error when setting widget in sidebar

Update: After setting the php version of website to 5.4 through the hosting panel, it worked but i think we shall check the issue for other users.

Here: https://codescar.eu/ you can see how i integrated a popover jQuery plugin into your plugin to show the titles of a day’s posts rather than leading right into the archives. Would you like to work with me and add this feature to your plugin?

Hello,
In the version 0.9.9 and 0.9.91 I used an annonymous php function that was supported only since PHP 5.4 but in the 0.9.92 I have replaced this function to suport older versions of PHP.

I don’t understand why you did get that error, The plugin does not use any ajax calls.

Nice feature, would you mind making it a WordPress plugin as an add-on for my plugin? I could make a note in the plugin that the widget can be extended.

Hello, i tried to install the plugin in 3 different sites running different WP versions [4, 3.9, 4] (on the same provider though with PHP setting 5.3.29) all produced the same error. That means the problem is located somewhere in the widget’s code and is not a WordPress issue. When you place the widget in the sidebar and press save, it triggers an ajax call that saves a widget’s settings etc.

Line 1801 is:

if ( $form = $wp_registered_widget_controls[$widget_id] )
	call_user_func_array( $form['callback'], $form['params'] );

apparently the $widget_id is set to ‘archives_calendar-2’. Maybe something fails and it gets 2 rather than 1, somewhere above and the problem only shows up here where the index ‘archives_calendar-2’ is needed but it should be ‘archives_calendar-1’