WordPress 4.3 just dropped and there are thousands of plugins that need to be checked BEFORE you update to WP 4.3!
Not to get too technical on you, and how I understand it, many plugin authors have used code for PHP 4 style constructors which are being deprecated in WordPress 4.3. This is especially true if the plugin you are using creates a widget.
Note: Starting in WordPress 4.3, regardless of the PHP version in use on a server, WordPress will throw a deprecated notice when one of the PHP 4 style constructors is called specifically for widgets. [Source: GitHub Gist]
So, to be safe, before updating to WordPress 4.3, please check ALL your plugins against this list of plugins that need to be updated. And read the comments in their post to see if authors have said they have updated and also check WordPress.org.
When at WordPress.org check out the plugins, authors, and/or updates/comments that you currently use. Please leave a comment or question if the plugin needs to be updated to work with WordPress 4.3.
Please note that some of the plugins have already been updated since the above list was made and if they have not been updated, please contact the plugin author to update.
If you are a plugin author, please see Aaron Jorbin’s article: Deprecating PHP4 style constructors in WordPress 4.3
UPDATE: Check out my article: Find Support if You Updated WP 4.3 and Have a Problem because you just might find a solution there if you are having problems with updating to 4.3.
If you are tired of doing updates all the time (or don’t do them at all) you can subscribe to one of my monthly update maintenance and security plans, called Tranquility Plans to always keep your web site healthy!