If you have an old Elementor-based theme and you upgraded elementor recently, you may notice an error like the one below :
PHP Fatal error: Uncaught Error: Class 'Elementor\\Scheme_Typography' not found

PHP Fatal error: Uncaught Error: Class 'Elementor\\Scheme_Color' not found

The above errors occurred because Scheme_Typography and Scheme_Color have been deprecated since elementor version 3.6.0.

How to fix the elementor Scheme errors :

This is not a straightforward fix. You need to get into code, and if you do not have experience, you should consider hiring a WordPress developer, to do the job.

STEP 1: You have to first, download the plugin or theme that’s causing the error. Then, you have to do a folder search for the following: Scheme_Color:: And Scheme_Typography:: to find out a list of all instances of the code that is causing the error.

STEP 2: You should replace all references of Scheme_Color with \Elementor\Core\Schemes\Color and Scheme_Typography with \Elementor\Core\Schemes\Typography.

Here are two examples given below.

/*** Example 1  ***/

//Old Code 
//'type' => Scheme_Color::get_type(),
//'value' => Scheme_Color::COLOR_1,

// New Code 
'type' => \Elementor\Core\Schemes\Color::get_type(),
'value' => \Elementor\Core\Schemes\Color::COLOR_1,

/*** Example 2 ***/

//Old Code 
//'scheme' => Scheme_Typography::TYPOGRAPHY_1,

// New Code 
'scheme' => \Elementor\Core\Schemes\Typography::TYPOGRAPHY_1,