Please refer to the upgrade instructions corresponding to your installation method.
AutoRouterInterface::getRoute() has the new second parameter string $httpVerb.
If you implement it, add the parameter.
The method signatures of ValidationInterface::check() and Validation::check()
have been changed. If you implement or extend them, update the signatures.
Version 4.3.6 did not alter any executable code in project files.
This is a list of all files in the project space that received changes; many will be simple comments or formatting that have no effect on the runtime:
composer.json