Back up problem

[sixxste]

Server operating system version

Windows Server 2016 Standard Ed. 64 bit

Plesk version and microupdate number

Plesk Obsidian 18.0.52 Update 3

Since few days, when I try to backup a WP webiste using the WP Toolkit, I'm getting an errore like

Unable to export database. Error message: -- Connecting to localhost...
-- Retrieving table structure for table wp_actionscheduler_actions...
mysqldump.exe: Couldn't execute 'select column_name, extra, generation_expression, data_type from in ...

I can't backup my website anymore, can please someone help?
Many thanks,
Stefano